=Paper=
{{Paper
|id=Vol-2197/paper7
|storemode=property
|title=Planning and Decision Support Tools for Integrated Water Resource Management on River Basin Level in South Africa on the Example of the Middle Olifants Sub-Basin
|pdfUrl=https://ceur-ws.org/Vol-2197/paper7.pdf
|volume=Vol-2197
|authors=Christian Jolk,Björn Zindler,Harro Stolpe,Roman Wössner,Andreas Abecker
}}
==Planning and Decision Support Tools for Integrated Water Resource Management on River Basin Level in South Africa on the Example of the Middle Olifants Sub-Basin==
https://ceur-ws.org/Vol-2197/paper7.pdf
Tagungsband UIS 2018
Beitrag G: Christian Jolk, Björn Zindler, Harro Stolpe, Roman
Wössner, Andreas Abecker
Planning and Decision Support Tools for Integrated Water
Resource Management on River Basin Level in South
Africa on the Example of the Middle Olifants Sub-Basin
Christian Jolk1, Björn Zindler1, Harro Stolpe1, Roman Wössner2, Andreas Abecker2
1
Institute of Environmental Engineering and Ecology, Ruhr University Bochum,
christian.jolk@rub.de
2
Disy Informationssysteme GmbH, andreas.abecker@disy.net
Abstract
This paper presents methods and software tools for GIS-based planning and decision support
in Integrated Water Resources Management. The approach results from the BMBF-funded
research project "Integrated Water Resources Management in the Pilot Region Middle Olifants
River, South Africa - MOSA". The tools developed provide an overview of quaternary river
basins in order to identify hot-spot areas with increased problem intensity with regard to water
quality and with a priority need for action.
Zusammenfassung
In diesem Beitrag werden Methoden und Softwaretools zur GIS-basierten Planung und
Entscheidungsunterstützung im Integrierten Wasserressourcenmanagement vorgestellt. Der
Ansatz resultiert aus dem BMBF-Projekt "Integrated Water Resources Management in the Pilot
Region Middle Olifants River, South Africa - MOSA". Die entwickelten Instrumente ermöglichen
einen Überblick über Flussteileinzugsgebiete vierter Ordnung, um Hot-Spot-Gebiete mit
erhöhter Problemintensität in Bezug auf die Wasserqualität und mit einem vorrangigen
Handlungsbedarf zu identifizieren.
1 Objectives
South Africa is facing major challenges in the water sector. The uneven distribution of
the water body network and of precipitation leads to water supply shortages especially
in the dry season. The water infrastructure and the management of water supply and
wastewater treatment are in deficit. The rapid industrial growth, the progressing
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urbanization and the industrially organized agriculture lead to increasing water demand
and water quality problems. The problems are increased by the fact that South Africa
has locations with significant touristic value.
Considering these challenges, different stakeholders, such as local and regional
authorities, NGOs, industry, and scientists, are searching for solutions to establish a
holistic and sustainable development of the water sector in the future. The integrated
approach of the R&D project MOSA, sponsored by the German Federal Ministry of
Education and Research (BMBF), helps to analyze and solve water-management
related problems in the Middle Olifants sub-basin.
The main project goal was to develop Planning and Decision Support Tools for Inte-
grated Water Resources Management (IWRM) on river basin level with the focus on
water quality issues. The Planning and Decision Support Tools (PDST) evaluate the
water resources and facilitate the identification and prioritization of sub catchments
with increased problem intensity and a necessity for action through IWRM measures.
The PDST improve and support decision processes of South African decision makers
in the water sector toward a cost-, time- and target-oriented approach.
The Middle Olifants sub-basin is a river basin with stressed water resources. The water
quality faces numerous challenges that require an efficient water management in the
future. The Water Quality Report of the Department of Water Affairs [Van Veelen 2011]
and the Planning Level Review of Water Quality in South Africa [DWA 2011] provide
an assessment of the water quality in the Olifants river basin in compliance with the
existing conditions in the area. According to the reports, the following water quality
problems arise in the Middle Olifants sub-basin and the Steelport:
• Increased salinity and eutrophication of dams and rivers by return flows from
agriculture and mining, as well as discharge from wastewater treatment plants
• Increased toxicity due to presence of pesticides and herbicides in the water
bodies
• Erosion caused by poor agricultural practice and overgrazing in rural areas
• Groundwater contamination due to inadequate wastewater treatment and
leakages from landfills and waste disposals
• High concentrations of sulphate and low pH values in surface water due to the
influence of mining, power plants and industry
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• Despite the fact of limited data in some parts of the sub-basin, increased heavy
metal concentrations are expected
Particular emphasis in the development of the PDST has been laid on the integration
of existing knowledge and experiences of South African stakeholders. The limited data
availability and quality as well as the uneven distribution of data among different
authorities and institutions influenced the development of the PDST.
2 Research Design and Activities
Since the International Conference on Water and the Environment and the United
Nations Conference on Environment and Development in 1992, IWRM attracted
worldwide attention, see, e.g., Agenda 21 [UNCED 1993]. According to the Global
Water Partnership (GWP), IWRM is “a process which promotes the coordinated
development and management of water, land and related resources in order to
maximize economic and social welfare in an equitable manner without compromising
the sustainability of vital ecosystems and the environment” [GWP 2000].
The overall objective of IWRM is “to satisfy the freshwater needs of all countries for
their sustainable development”. With the focus on water planning, IWRM should
include “the development of interactive databases, forecast models and economic
planning models appropriate to the task of managing water resources in an efficient
and sustainable manner will require the application of new techniques such as
geographical information systems and expert systems to gather, assimilate, analyze
and display multisectoral information and to optimize decision-making.” [UNCED
1993].
3 Administration / laws
In order to discuss the water quality issues on a national level the Department of Water
Affairs (DWA) published the series “Water Resources Planning System Series” [DWAF
2006a, b]. This series deals with political processes, strategies and management tools
for assessing the water quality.
According the statement of the DWAF [DWAF 2006b] “Integrated water quality
management should be implemented in a cyclical process aimed at continual
improvement (fundamental to the principle of adaptive management). This cycle
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occurs at a number of different levels. They range from individual (local) source and
resource management initiatives (short-term) through re-consideration of the
catchment management strategy (medium-term) to re-consideration of the resource
directed measures and vision (long-term).”
Following the DWA [DWA 2011] “water quality planning is directed at addressing the
following key issues facing water resource management:
• Balancing the degree to which water, and water quality, is used (e.g. for socio-
economic development) with the degree of protection of water resources as
natural systems (for current and future generations) requires both political and
scientific considerations.
• The nature of the imbalance between the requirement for and supply of water
and water quality is such that equitable allocation of these resources is not
possible without management intervention.
• Resource directed management of water quality requires certain specialist
skills, while decision-making is often complex and may have to be based on
uncertain or incomplete data and information.
• Consistent nationwide application of legislation relating to management of water
quality is essential.”
To assess the water quality according to the National Water Resource Strategy [DWAF
2004a; DWAF 2004b] and the Resource Directed Management of Water Quality
[DWAF 2006a, b], the approaches adopted in these reports are, on the one hand,
resource-oriented measures to protect water resources and, on the other hand,
measures to control the pollution sources.
An assessment of the water quality of all river basins in South Africa is reported in a
study of the DWA [DWA 2011]. This study provides information on the assessment of
point and diffuse sources, the environmental conditions of the river basins as well as
the impact of human activities on water resources and ecosystems.
The PDST presented in this paper follow the strategy of the DWAF [DWAF 2004a;
DWAF 2004b] and improve and specify the methodology of the DWA [DWA 2011] on
the example of the Middle Olifants sub-basin.
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4 Project area
The investigated Middle Olifants sub-basin is located in the provinces Limpopo,
Gauteng and Mpumalanga in the Northeast of South Africa.
Starting at the outlet of the Loskop Dam the Olifants flows in northern direction until it
joins the Flag Bohilo Dam. Larger tributaries in this river section are the Moses and the
Elands. After the Olifants leaves the Flag Boshilo Dam, it is deflected to Northeast by
the Wolkenberg Mountains. At the confluence of the Steelport and the Olifants, the
middle river section of the Olifants ends.
The massif of the Wolkenberg Mountains consists mainly of intrusive rocks.
Furthermore, extensive sheets of basalt are located in the Springbok Flats, an area in
the western part of the Middle Olifants sub-basin. Quaternary deposits can be found in
the river valleys and the flood plains. In particular, the basalts are aquifers with high
yield.
A large part of the Middle Olifants sub-basin is used for agriculture. Predominately
maize is grown in rain-fed agriculture. Soybean, cotton, vegetable, citrus fruits, wheat
and tobacco are grown on irrigated fields. Large irrigated areas are found in the river
valleys of the Olifants, the Elands and the Moses in close proximity to Loskop Dam
and Flag Boshilo Dam. Rain-fed agriculture is found primarily in the Springbok Flats or
in areas east of the Olifants.
Main water users are the agriculture for irrigation purposes and the rural and urban
population for drinking water supply. Other important water users are hydro-electrical
power stations and mines.
5 Methods
The applied method follows the basic ideas of risk assessment for water quality. It is
based on concepts for the ecological risk analysis which have been originally
developed in Germany, for example by Kiemstedt and Bachfischer [Kiemstedt &
Bachfischer 1977] and which have been completed later during the further
development according to the European Law of Environmental Impact Assessment
from 1985 and amended in 1997, 2003 and 2009 [EC 2011]. Comparing to the
European concept, the Environmental Protection Agency in the United States
published their Guidelines for Ecological Risk Assessment in 1998 [EPA 1998].
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The developed method consists of a contamination risk assessment (water quality).
The basic idea for the contamination risk assessment is to combine contamination
potentials (originating from land uses) and the sensitivity of natural resources (here of
water resources) which results in a contamination risk. Two-dimensional matrices are
used to aggregate the contamination potential and the sensitivity of water resources
into the risk. The matrices are applied to determine the risk on a scale with the classes
“low”, “medium” and “high” [Jolk 2010; Greassidis 2011; Zindler 2012].
The quaternary catchments are the spatial basis on which PDST are being applied.
The PDST are instruments to spatially identify and prioritize contamination risks (e.g.,
diffuse agricultural contamination sources or industrial point sources). The
Contamination Risk Tool is used for risk assessment of water quality aspects
(groundwater and surface water). The Ranking Tool identifies quaternary catchments
with high problem intensities and priority need for IWRM measures.
The PDST are GIS-based. They enable the user to visualize single current situations,
the contamination risk assessment and the prioritization (ranking) of quaternary
catchments.
5.1 Contamination Risk Tool
The Contamination Risk Tool is used to analyze the contamination risk of water
resources in a quaternary catchment. The method described below is based on the
estimation of the sensitivity of water resources (groundwater and surface water) and
the classification of contamination potentials from different sources, developed in a
preceding R&D project about IWRM in Vietnam.
The method has been transferred to and adapted on South African conditions. Based
on the currently higher data resolution in South Africa the methodology was further
developed in order to increase the accuracy of the conclusions. As already stated
above, the basic idea can easily be summarized by the equation:
Sensitivity of water resources + Contamination potential of polluters
= Contamination risk
The contamination risk assessment is being conducted and evaluated for three
contamination paths of pollutants that affect the water resources:
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• Infiltration (into groundwater): Solute pollutants from diffuse and point sources
directly infiltrate into the groundwater (e.g., nitrate from agricultural sources,
domestic wastewater, industrial wastewater, mine water)
• Erosive runoff (into surface water): Pollutants from diffuse sources are being
transported by (erosive) runoff into the surface water (e.g., phosphate and
pesticides from fields adsorbed to sediments or organic matter).
• Direct discharge (into surface water): Pollutants from point sources are being
discharged into the surface water (e.g., domestic wastewater, industrial
wastewater, mine water, seeping landfills).
The contamination potential describes the ability of a certain polluter to negatively
affect the water resources. It is graded into four classes (no, low, medium, high). Only
the most relevant polluters for the evaluation of contamination risks in each path have
been selected for closer evaluation [Zindler 2012 (with reference to South African
conditions)].
The sensitivity of water resources describes the relative ease of a contaminant applied
on or near the land surface to migrate into the water resource. It is a function of different
natural characteristics. The sensitivity is graded into five classes (no, low, medium,
high, very high). If more than one parameter is being considered to assess a sensitivity
class, matrices help to aggregate different class values into a final class. Parameters
considered to assess the sensitivity of groundwater are the aquifer type and areas with
an intense use of groundwater. The sensitivity of surface water is assessed according
to the parameters of potential soil erosion and the ecological status. The specific
regional characteristics of the different project areas are considered [Zindler 2012 (with
reference to South African conditions)].
The tool identifies hot spot quaternary catchments regarding the risk of contamination
for water resources and helps decision makers to analyze contamination potentials
from different sources.
The following subsections give an overview of the combinations leading to the
qualitative water risk assessment and the resulting available maps. These maps are
compiled in a planning atlas. Disy developed a web-viewer version of the atlas [Jolk
2010; Greassidis 2011; Zindler 2012].
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5.1.1 Contamination path 1: infiltration of contaminants into groundwater
Contamination path 1, groundwater sensitivity
The resource sensitivity of groundwater is established for the uppermost groundwater
aquifer, also taking into consideration groundwater use.
Groundwater resource sensitivity is classified based on runout and groundwater use
(e.g., solid rock with high runoff (basalt) = high groundwater resource sensitivity or solid
rock with low runoff (granite) = low groundwater resource sensitivity) [Barnard & Baran
1999] [Du Troit et al. 1998; Du Troit et al. 1999; Du Troit et al. 2003]. The runout
evaluation of the uppermost groundwater aquifer was carried out based on the
hydraulic conductivity classes in hydrological cartography for North Rhine Westphalia
NRW [LANUV NRW 2010]. Overlying strata above the groundwater aquifers were not
included in the consideration, as these cannot be safely assessed in the chosen scale
of 1:800.000. As the protective effect of overlying strata is ignored, the classification of
resource sensitivity lies within secure margins.
Areas with high groundwater use (wells) are characterized by high resource sensitivity.
This characterization is based on existing risks through contaminant inflow due to
unprofessional well construction or well use. A further justification for this
characterization is the special need for protection of the directly used groundwater
resource.
Contamination path 1, contamination potential
a) Contamination potential of diffuse sources through infiltration of agricultural
contaminants
For agricultural areas, a contamination potential through infiltration of nutrients is
assumed. The nutrient availability potential is differentiated according to different land
use classes [Moolman et al. 1999]. The agricultural areas were defined based on the
South African National Land-Cover Database [Fairbanks et al. 2000]. All agricultural
areas are classified due to their nutrient availability potential in three contamination
potential classes (high, medium and low) [Moolman et al. 1999].
b) Contamination potential of diffuse sources through infiltration of settlement
wastewater
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Settlements are assumed to have a contamination potential through wastewater
infiltration. There are wastewater treatment plants in the Middle Olifants sub-basin but
because of the improper operation of the plants and the predominant renovation
backlog it could be expected that wastewater is infiltrating.
Settlement density and the location of single houses are used as a basis to classify
contamination potential. It is assessed by using topographical maps of South Africa
(1:50.000).
The classification of contamination potentials from diffuse sources through wastewater
infiltration is carried out according to settlement classes in three grades (e.g.,
Metropolitan area = high contamination potential or rural scattered = low contamination
potential).
c) Contamination potential of point sources through infiltration of contaminants
For point sources such as commercial, industrial facilities and mines, a contamination
potential through infiltration of contaminants is assumed. It is considered that most of
these facilities do not yet take sufficient actions for groundwater protection.
A comprehensive registry with applied substances is not yet available or still being set
up by the authorities. For an initial evaluation on river basin level the topographical
maps of South Africa (1:50.000) as well as data of the Ministry of Mineral Resources
were used.
By analyzing aerial images an exact site localization of the point sources has been
done. All locations were assigned by a sphere of influence (500 m) along the lines of
the EU Water Framework Directive [Raschke & Menzel 2005].
The classification of the contamination potential classes is based on the production
branches and the types of mineral being exploited in the different mines (e.g., clay
dumps = low contamination potential or PGM mines = high contamination potential)
[Gauteng Department of Agriculture, Environment and Conservation 2008].
Contamination path 1, groundwater contamination risk
The groundwater contamination risk is the result of the aggregation of groundwater
resource sensitivity and the corresponding contamination potential. Figure 1 shows an
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example of the aggregation matrices which have been developed for each intersection
operation respectively.
Very high No Very high Very high Very high
Sensitivity High No Medium High High
groundwater Medium No Low Medium High
Low No Low Low Medium
Path 1 - None Low Medium High
Contamination risk
Contamination potential agriculture
agriculture
Figure 1: Path 1 – Groundwater contamination risk through infiltration of agricultural contaminants
Figure 2 depicts the groundwater contamination risk due to infiltration of agricultural
contaminants in the Middle Olifants sub-basin.
Figure 2: Path 1 – Groundwater contamination risk due to
infiltration of agricultural contaminants
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5.1.2 Contamination path 2: erosive runoff and/or erosive discharge of
contaminants into surface waterbodies
Contamination path 2, surface water sensitivity
Erosion
To analyze the erosive runoff and/or erosive discharge of contaminants into surface
water bodies, the methodology of Moolman [Moolman et al. 1999] is used to estimate
the sediment availability potential. The sediment availability potential is calculated by
aggregating the wash-off potential with the sediment production potential.
A GIS-based intersection of Moolman [Moolman et al. 1999] was used to calculate the
sediment production potential.
Water withdrawal
Starting from the analysis of the drinking water withdrawals at dams and the surface
water, areas have been identified in which water contaminations can have a negative
impact on the reservoirs and drinking water abstraction points. Detailed information on
water withdrawals are available from the studies "Development of a reconciliation
strategy for all towns in the Northern Region", at the municipal level, commissioned by
the Department of Water Affairs (Directorate: National Water Resources Planning).
Ecological status
Potentially sensitive areas could be identified based on a study [Nel & Driver 2012] by
the Council for Science and Industrial Research (CSIR) and the South African National
Biodiversity Institute (SANBI) on environmental protection areas.
Regarding the research of Nel, both aquatic ecosystems and wetlands as well as fish
sanctuaries and protection areas with priority are included in the sensitivity analysis.
The most important context in which the “Freshwater Ecosystem Priority Areas“
(FEPAS) can be institutionalized is the development of the Resource Quality
Objectives (RQOs) which, according to DWAF [DWAF 2004a; DWAF 2004b], has to
be designated on the national level. It should also be noted that the DWA
acknowledges the FEPAS to derive the RQOs [Nel et al. 2011]. The ultimate definition
of the RQOs was not completed at the time the report was written [DWA 2014].
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FEPA regions include, on one hand, the current and planned fish sanctuaries with a
good ecological status (Ecological Category A or B) as well as wetland cluster and, on
the other hand, the categories “Fish Support Area" and "Upstream management area".
Fish sanctuaries within a region with an ecological category worse than B are called
"Fish Support Areas". "Upstream Management Areas" are sub quaternary catchments
where human activity must be controlled in order to prevent the degradation of
downstream FEPAS and "Fish Support Areas" [Nel et al. 2012].
The evaluation of surface waterbody resource sensitivity was categorized as “very
high”, “high”, “medium” and “low”.
Contamination path 2, contamination potential
• Contamination potential of diffuse sources through erosive runoff of agricultural
contaminants
For agricultural areas, a contamination potential through infiltration of nutrients is
assumed. The nutrient availability potential is differentiated according to different land
use classes [Moolman 1999]. The agricultural areas were defined based on the South
African National Land-Cover Database [Fairbanks 2000]. All agricultural areas are
classified due to their nutrient availability potential in three contamination potential
classes (high, medium and low).
Contamination path 2, surface waterbody contamination risk
As shown in figure 3, the surface waterbody contamination risk results from an
aggregation of the erosion and the contamination potential from diffuse agricultural
sources due to erosive runoff of agricultural contaminants and the surface waterbody
resource sensitivity (ecological status).
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Very high No Very high Very high Very high
Sensitivity High No Medium High High
surface water -
Erosion Medium No Low Medium High
Low No Low Low Medium
None Low Medium High
Contamination potential
agriculture - Erosion Contamination potential agriculture
Very high No Very high Very high Very high
Sensitivity High No Medium High High
surface water Medium No Medium Medium High
Low No Low Medium High
Path 2 - None Low Medium High
Contamination risk
Contamination potential agriculture - Erosion
agriculture
Figure 3: Path 2 – Surface waterbody contamination risk due to
erosive runoff of agricultural contaminants
Figure 4 depicts the surface waterbody contamination risk due to diffuse discharge of
agricultural contaminants.
Figure 4: Path 2 – Surface waterbody contamination risk due to
diffuse discharge of agricultural contaminants
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5.1.3 Contamination path 3: direct discharge of contaminants into surface
waterbodies
Contamination path 3, surface water use sensitivity
The surface water use sensitivity follows the same approach as the surface water
sensitivity (path 2) for the ecological status.
In addition to this, the use of surface water (drinking water abstraction points at dams
and surface water) as well as the environmental protection status were taken into
account. Detailed information on water withdrawals are available from the studies
"Development of a reconciliation strategy for all towns in the Northern Region", at the
municipal level, commissioned by the Department of Water Affairs (Directorate:
National Water Resources Planning).
Starting from the analysis of the drinking water withdrawals at dams and the surface
water, areas have been identified, in which water contaminations can have a negative
impact on the reservoirs and drinking water abstraction points.
Contamination path 3, contamination potential
a) Contamination potential due to direct discharge of wastewater from settlements
Settlements are assumed to have a contamination potential through direct discharge
of wastewater. There are wastewater treatment plants in the Middle Olifants sub-basin
but because of the improper operation of the plants and the predominant renovation
backlog it could be expected that untreated wastewater is discharged into the rivers.
Based on the evaluation of the wastewater treatment plants in the Middle Olifants sub-
basin by the Green Drop Report [DWA 2012] and studies of REMONDIS [REMONDIS
2012] the classification of the contamination potential could be done. The cartographic
data are based on the topographic maps of South Africa at a scale of 1:50,000.
According to the wastewater treatment plants performance from low to high, the
contamination potential is classified respectively into high to low. Downstream effects
are included in the evaluation and the worst case is assumed. The wastewater load is
considered to be constant and self-cleaning processes of the rivers are not considered.
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b) Contamination potential due to discharge of wastewater from point sources
For point sources a contamination potential through direct discharge of contaminants
is assumed. It is considered that most of these facilities do not yet take sufficient
actions for surface water protection.
By analyzing aerial images an exact site localization of the point sources has been
done. All locations were assigned which are located in a 200 m distance to the next
river, along the lines of the EU Water Framework Directive [Raschke & Menzel 2005].
The classification of the contamination potential classes is based on the production
branches and the types of mineral being exploited in the different mines (e.g., clay
dumps = low contamination potential or PGM mines = high contamination potential)
[Gauteng Department of Agriculture, Environment and Conservation 2008].
Contamination path 3, surface waterbody contamination risk
The surface waterbody contamination risk is the result of the aggregation of
contamination potential and resource sensitivity for surface waterbodies. The
emphasis here lies in drinking water applications and the ecological protection status.
As an example of the general approach, figure 5 represents the aggregation to
establish the contamination risk due to wastewater discharge from settlements.
Very high No Very high Very high Very high
Sensitivity High No Medium High High
surface water Medium No Low Medium High
Low No Low Low Medium
Path 3 - None Low Medium High
Contamination risk
Contamination potential settlements
settlements
Figure 5: Path 3 – Contamination risk for surface waterbodies due to discharge
of wastewater from settlements
Figure 6 depicts the resulting contamination risk for surface waterbodies due to
wastewater discharge from settlements.
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Figure 6: Path 3 – Contamination risk for surface waterbodies due to discharge
of wastewater from settlements
5.2 Ranking Tool
The Ranking Tool processes the results of the Contamination Risk Tool (aggregated
on quaternary catchment basis) in order to prioritize the problem intensities of
quaternary catchments within a river basin regarding their water quality issues.
For this ranking, the percentage of areas with a “very high” or “high” contamination risk
of the entire quaternary catchment respectively the location of point sources and their
contamination risk were joined up and divided into three ranking classes. Initially this
was done separately for each contamination path. Within each of the contamination
paths a ranking was carried out for each contamination risk (e. g., figure 7).
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Figure 7: Result of ranking: contamination risk for the groundwater stemming from agriculture
5.3 Software implementation
A software tool based on the methodological approach combines a spatial data
warehouse system and a Web-based Geographic Information System (Web-GIS). The
solution is implemented using the Disy Cadenza platform [Vogel et al. 2010] for spatial
reporting solutions. Disy Cadenza is usually applied as follows (see figure 8):
• Existing spatial geodata and factual data as well as information from manifold
heterogeneous existing sources (databases, existing GIS, files, geodata
services) can be imported and stored in a unified and harmonized spatial Data
Warehouse.
• The process of filling the Data Warehouse with incoming data may comprise
operations for selecting the project-relevant data from different sources,
checking or improving data quality, transforming data such that syntactic and
semantic integrity and consistency is achieved, and loading the data into one or
more specific data schemata which facilitate human understanding or which
enable more efficient execution of analytics functions etc. The totality of such
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data-manipulation operations is called ETL process (extract – transform – load
operations, cp. [Schrauth et al. 2017]).
• Cadenza allows building up a repository of operation sequences for querying,
analyzing and processing the data in the Data Warehouse and for finally
visualizing und publishing the analysis results as thematic maps, business
diagrams, predesigned PDF reports, etc. The so-defined data-analysis
workflows in the repository can be managed with the help of a fine-grained user
and rights management.
• The Cadenza functionalities and results can be accessed through a desktop tool
(Cadenza Professional), a Web-GIS (Cadenza Web), a Tablet-based mobile
solution (Cadenza Mobile) and through OGC-compliant geodata Web services.
Figure 8: Elements of the Cadenza software platform for spatial data warehousing
and spatial reporting solutions
The above-presented risk assessment method has been implemented using Cadenza
as follows (see figure 9, from left to right):
• Raw geodata from the South-African government, needed to assess the
contamination paths 1, 2 and 3, were loaded into the geodata warehouse. As
part of the ETL processes, data quality was checked and necessary scale and
representation changes were done. The geodata warehouse is based on
PostgreSQL/PostGIS. Data is load into an application-specific DB-schema.
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• The computations of contamination potential, resource sensitivity and
contamination risk were implemented as part of the ETL processes, as well as
the ranking of quaternary catchments according to their priority for action needs.
Concretely, these processes were realized through stored database procedures
in the data warehouse (Groovy scripts and PL/pgSQL functions).
• The data warehouse then contains all basic as well as all derived parameters
required for IWRM planning and decision making. This information was
visualized as thematic maps that are provided to end users in the South-African
public administration through their Web browsers with the help of the Cadenza
Web-GIS. Furthermore, all the thematic maps visualized in the Web-GIS can
also be exported for offline-use during on-site operations using a tablet and the
Cadenza Mobile tool [Otterstätter at al. 2014; Lübke et al. 2016].
• Another feature, implemented with the help of the Cadenza Report Generator
tool, is the possibility to preconfigure a document template for collecting all the
information available in the system for a certain region. At any time when up-to-
date information about this area is required, the report generation can be run
and a bulletin for the region in quest can be created on demand.
Figure 9: Simplified data-flow of the realized software solution
As an example, figure 10 shows the DB tables stored in the data warehouse for the
realization of the computations regarding contamination path 1, infiltration of
contaminants into groundwater, caused by agriculture, diffuse sources in settlements
and point sources. The tables with a red exclamation mark contain input data whereas
all the other tables are derived by GIS operations or automated risk assessment and
ranking procedures, based on the qualitative decision tables as shown, e.g. in figure
1.
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Figure 10: Database tables used for the realization of contamination path 1, infiltration of
contaminants into groundwater, caused by agriculture, settlements and point sources
For instance, the table „quality_cp_agriculture“ describes the contamination potential
from agricultural activities and is created on the basis of land-use maps; the table „qua-
lity_cr_gw_settlements“ describes the contamination risk (cr) of groundwater (gw),
coming from settlements – which can also be found in land-use maps. The conta-
mination risk of groundwater caused by agriculture („quality_cr_gw_agriculture“) is de-
rived by merging data about groundwater sensitivity and about contamination potential
by agricultural activities („quality_gw_sensitivity“ and „quality_cp_agriculture“). The
sensitivity again, as explaied above, can be derived from (hydro)geological maps. For
assessing the urgency (ranking) of water management interventions in a certain region
(water management unit, WMU, a quaternary catchment area), the water usage must
also be taken into account.
To give an impression of thematic coverage and volume of information in the data
warehouse, we present some facts about the data acquired for our project region:
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• Path 1: infiltration of contaminants into groundwater:
o 170 different sensitivity regions have been identified and about 750 geo-
graphic areas were classified as „very high“, regarding sensitivity.
o With respect to contamination potential, ca. 40.000 land-use areas
and/or agriculture-related risk areas have been identified, as well as
more than 60.000 settlements and/or risk areas because of settlements,
as well as about 250 point sources as risk areas.
• Path 2: erosive runoff and/or erosive discharge of contaminants into surface
waterbodies:
o In addition to several tens of thousands risk areas because of agricultural
activities, 630 different sensitivity regions have been identified.
• Path 3: direct discharge of contaminants into surface waterbodies:
o 630 different sensitivity regions have been examined.
o Regarding the contamination potential, ca. 650 areas close to surface
waterbodies and with a potential influence by settlements have been
identified, as well as ca. 115 areas close to surface waterbodies and with
a potential influence by point sources.
• Geographic base data, base maps, supplementary data and material:
o Definition of 39 water management units.
o 536 water bodies.
o 160 lithological formations, 300 different soil areas, 164 biomes.
o 1.600 drainage lines, 102 barrages and dams, further cadaster informa-
tion about water supply pipes and water infrastructure.
o 60 cities and 2.814 urban areas.
o 23 Water Treatment Plans.
o Average annual evaporation as well as data about population density.
The sheer amount and the diversity of relevant data – only for a relatively small part of
South Africa – gives already an impression that – even for such a relatively coarse-
grained IWRM approach at the WMU level, the operational use of such an academic
result makes it indispensable to automate all processing steps as much as possible, to
put automated data integration and data quality procedures in place and to
continuously update and actualize the database in use. Manual data acquisition or
maintenance will never be economically accepted for a continuous operational use.
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Figure 11: Web-GIS presentation of contamination risks coming from agriculture (path 1)
Figure 11 to figure 13 illustrate some of the planning maps created by the system and
accessible through the Web-GIS. Figure 11 presents contamination risks caused by
agriculture, shown here in combination with locations of wells. In contrast to this high-
resolution visualization, Figure 12 aggregates the risk assessment at the WMU-level
and shows the WMU ranking with a simple red/green/yellow colouring. The most
aggregated risk-assessment visualization is shown in figure 13. Here, each WMU is
presented with a red/green/yellow colour-coded overview diagram with six circle
segments, each of which represents the risk ranking for one of the six paths: (1)
contamination risks from agriculture through path 1; (2) contamination risks from
settlements through path 1; (3) contamination risks from point sources through path 1;
(4) contamination risks from agriculture through path 2; (5) contamination risks from
point sources through path 3; (6) contamination risks from agriculture through path 3.
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Figure 12: Web-GIS presentation of WMU ranking of contamination risk from settlements (path 3)
Figure 13: Combined Web-GIS presentation of six different contamination paths
All the thematic maps and planning maps created by the system can also be exported
for offline usage with the Cadenza Mobile solution. This may be useful for field workers
inspecting the situation on-site or acquiring or checking geographic data in-situ. Here,
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the offline feature is important because good Internet connection may not be available
everyhwere in the hinterland.
Moreover, for each WMU, an up-to-date data summary and a set of WMU-related
thematic and planning maps can, at any time, be extracted and compiled into a
preconfigured PDF-report template, thus creating an always actual “WMU bulletin” for
decision makers.
6 Outcome, Impact and Outlook
The application of PDST will enable South African stakeholders to make decisions on
a scientific basis. The identification process enables decision makers to attend
effectively to the issues with high priority ratings first. The close cooperation of the
project and the South African authorities ensures a holistic implementation of the tools.
Since 2015, the project implemented the Web-based system at the Department for
Water and Sanitation (DWS) in Pretoria. The participation of the responsible water
agency on national level guarantees a sustainable adjustment and a nation-wide
transferability of the method to South African conditions.
The PDST identify quaternary catchments with higher need for action and give a
structured overview of the causes. They allow for a layered, problem-orientated and
efficient examination of entire river basins in South Africa. They initially use a
systematic overview examination (scale approx. 1:800.000) in order to identify
quaternary catchments with higher problem intensity and prioritized need for IWRM
measures (“hot spots”). The next step should be the development of methods to
examine these previously prioritized quaternary catchments in more depth (scale
approx. 1:50.000) in order to ascertain the types, extensions and locations for
necessary IWRM measures.
From the software-technological point of view, the automation of data integration, data
quality assurance and risk assessment was absolutely necessary for the long-term
sustainable use of the system. Feedback from local stakeholders also showed great
interest for the mobile and offline GIS. Especially in developing and emerging
countries, such a solution with a full-fledged mobile cadastral system could be a good
tool for stepwisely completing and improving the official geo-database about water
infrastructures etc. Looking at potential future RTD topics, some areas of potential
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interest might be (i) some standardization of data models and/or ontologies about the
water sector and IWRM; (ii) coupling of coarse-grained and general models and system
assessments with more fine-grained and real-time data (water quantity, water quality,
water demand) or also with results from hydrologic modeling for early-warning
systems, mid-term planning, model calibration, etc.; (iii) combination of IWRM planning
support with scenario-based planning for designing future systems taking into
consideration different potential devleopments (climatic, economic, …).
Some first steps in these directions are currently being undertaken in ongoing projects,
but there is still much space for future developments.
Acknowledgment. The work presented here has been supported by the German
Ministry for Education and Research (BMBF) through the project “IWRM Südafrika -
Integriertes Wasserressourcenmanagement in der Projektregion Mittlerer Olifants”
(grant 033L048). The methods and tools are currently being further developed in the
BMBF-funded project “iWaGSS: Entwicklung und Erprobung eines innovativen
Wassergovernancesystems zur Linderung von Wasserstress und zur voraus-
schauenden Wasserbewirtschaftung in Regionen mit überbeanspruchten Wasser-
ressourcen in Afrika und weltweit” (grant 02WGR1424) funded within the BMBF
research programme “GroW – Globale Ressource Wasser”.
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