ITS3.2/HS1.1.8

Groundwater resources in African drylands are important sources of freshwater but are under pressure due to population growth and climate change. It is therefore increasingly important that groundwater resources are managed in a sustainable way. Development of IWRM plans are ongoing in (semi-)arid African countries with support from national governments, NGOs and consultancies. This presentation aims to highlight two case studies in which bio-geophysical and socio-economic data were combined to assist in the Integrated Water Resources Management (IWRM) process: 1) catchment-scale Water Infrastructure Assessment (WIA) in Sudan and 2) assessment of pathways towards sustainable groundwater use in African drylands. Per case study lessons learned and recommended approaches are provided.

In IWRM intervention planning for semi-arid regions a local increase in available water resources is sought after, which can be found in the better use of excess runoff. A balance between water demand and water resources on community level is key and a prerequisite for implementing durable and inclusive interventions that last. The IWRM process starts with a strong knowledge base. In practice, however, the development of a good knowledge base is not simple. Challenges arise in collecting, processing, and mapping results. With hydrogeology, a 3D situation is translated to 2D maps. Socio-economic data are often stored based on administrative boundaries and need corrections for hydrological source-area delineation and seasonal and interannual variations. Population density and water demand change over seasons, following crop cycles and livestock migration patterns. Looking at local water availability, rainfall and surface water flows are becoming more variable and less reliable. Therefore, assessment of the rainfall regime and corresponding behaviour and movements of people and livestock is key. For WIAs, yields and usage are often averaged, thus disregarding seasonal changes, even though shallow wells and reservoirs regularly become depleted outside the rainy season. The Sudan case study presents an improved approach for a WIA, that is adaptable and can be applied in semi-arid environments in Africa and elsewhere, in which seasonality and socio-economic dynamics were taken into account.

Both hydrogeologic and socio-economic conditions tend to be quite location-specific. This makes developing a simple blueprint for integrated groundwater management impossible. However, by translating local conditions into regional advice, strategic pathways were developed for the drylands of Africa[1] to support IWRM. The zonal hydrogeological and socio-economic setting determined the main groundwater issues and the potential sustainability strategies. The sustainability pathways describe potential sets of strategies that can be effective in moving towards sustainable groundwater resources development and use. While these pathways provide insight into regional differences within the African drylands, these cannot be used at local scales. Tailor-made approaches are necessary. In these assessments, remote sensing provides opportunities. Gridded datasets of population density are of great value in water demand assessments on a larger scale. Participatory stakeholder processes also provide opportunities, including group interviews for development of community calendars providing useful information on the occurrence and frequency of natural hazards and water demand.

How to cite: Van der Heijden, A., Waterloo, M. J., Gevaert, A. I., and Benedicto van Dalen, D.: Integration of hydrogeology and social sciences in practice, two IWRM case studies with challenges and opportunities from semi-arid Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7114, https://doi.org/10.5194/egusphere-egu22-7114, 2022.

Developing green infrastructures (GIs) for rainwater harvesting has prevailed in many arid regions, which requires a new water management framework. This paper focuses on a water policy - water trading scheme – design and analysis for integrated green infrastructures and water resource management in a watershed that consists of multiple urban areas. A multiagent model bringing together urban water management and GIs planning models for multiple water managers with hydrological models is proposed to show 1) what the optimized water trading scheme is, 2) how the scheme would affect watershed socio-hydrologic environments, and 3) what the role of GIs in the scheme is. In the model, the water trading scheme design depends not only on the hydrologic dynamics of watershed caused by GIs and but on the social interactions between watershed and multiple urban managers. The proposed model is applied to the Colorado River Lower Basin, which is one of the USA's aridest regions and is planning water trading. Results indicated that a water-trading scheme effectively allocates limited water resources with a minimized system cost in the study area. Results also show that developing GIs to use rainwater resources might further reduce the cost induced by the water trading scheme. However, it might also exacerbate water resource allocation inequity among water users. These findings can help decision-makers design the associated water policy to support sustainable watershed development in arid regions.

How to cite: Zhang, M. and Chui, T. F. M.: Modeling water trading to support integrated green infrastructure and water resources management in an arid watershed, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3487, https://doi.org/10.5194/egusphere-egu22-3487, 2022.

Water extraction in Bengaluru, India's fastest expanding metropolis, entirely depends on its ~500000 wells in a crystalline rock aquifer, of which an unknown number has been abandoned and the level of others has sunk to depths of 450 meters below surface. Recent research has highlighted the spatial heterogeneity and questioned the reliability of water level data in these settings. To fill existing knowledge gaps on the likely over-extraction of groundwater as a vital resource we used a socio-hydrogeological approach of front-lining local hydrogeologists to collect primary data on the spatio-temporal evolution of well depths across the city. Our data show that over the past 60 years borewell depth has increased significantly while water yields have remained unchanged, indicating that digging deeper wells is unsustainable. Using camera inspections of 56 wells in a 2.1km² catchment of industrial land use in Electronic City of Bengaluru, we noted that water levels in the wells are largely determined by rock fractures, not by well depth. Our data show that increased borewell depths is a good signal of declining water levels in Bengaluru’s aquifers. Analysis of δ¹⁸O and δ²H signatures of groundwater samples across all depths followed the local meteoric water line indicating recent recharge, implying that drilling deeper only increased the borehole volume and did not tap into newer water sources.

How to cite: Kulkarni, T., Gassmann, M., Kulkarni, C., Khed, V., and Buerkert, A.: Assessing the groundwater sustainability of Bengaluru megacity, India, through the lens of socio-hydrogeology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2135, https://doi.org/10.5194/egusphere-egu22-2135, 2022.

Coastal Mediterranean lagoons are very often groundwater-dependent hydrosystems, however their hydrogeological functioning is poorly known, damaging their management. Socio-hydrogeology allows, in an inter-and transdisciplinary way to clarify the relationships linking human activities and groundwater status. Those interactions within the watershed, combined with consumption patterns of the population, and sanitation defects can generate processes leading to pollutant fluxes with impacts on surface water, groundwater and lagoon water quality. This approach integrates both social and economic components into hydrogeological investigations.

The Biguglia lagoon watershed (Northern Corsica, France) has been chosen as a pilot site. Indeed, significant nitrate content, emerging compounds, and pesticides have already been observed in the lagoon waters, but their origin still needs to be specified, both in terms of source and dispersion modalities.

The aim of this study is to (1) assess the link between groundwater quality and the anthropogenic pressures on the watershed, (2) understand water users’ and the stakeholders ‘perception and knowledge of the watershed and the local territory, (3) identify the origin of pollutions detected in the lagoon’s water.

In this purpose, a field sampling was led in spring 2021, combining several tools useful for the knowledge improvement of the hydrogeological functioning and the tracing of anthropic pollutant fluxes. Investigations with structured interviews was administered to 32 water users and 16 local stakeholders involved in the monitoring assessment, to determine the land use evolution since 1950’s to present and aiming at identifying past and present uses of the water resource over the watershed. At the same time, a multi-tracer water sampling, combining physico-chemical parameters, major ions and trace elements as well as, stable isotopes of the water molecule was carried out on 53 points (lagoon, rivers, canals waters, groundwater), of which 21 samples were also analysed for a set of pesticides (screening of 240 molecules).

Pesticide’s analysis show that the study site is affected by agricultural pollution. Indeed, neonicotinoid insecticides, extensively used worldwide, have been found on the sampling points with significant concentrations. Those pesticides are mainly used in fruit, vegetable and cereal crops. The field survey, the questionnaire and the sampling campaign have allowed to identify and confirm the presence of these cultures on the study site. In the same way, benzotriazoles, perfluorinated acids (PFAs) and DEET (insect repellent) have also been detected. They are related to the consumption habits of the population on the watershed.

Geochemical analysis correlated with the social analysis and the land use analysis permitted to better constraint pollution sources, evidencing two main sources: sanitation defect and agriculture activity.

The socio-hydrogeological approach is essential to improve the knowledge of the Biguglia lagoon hydrosystem. The purpose of this work is to offer a new functional diagram of the area, including the space-time continuum of anthropogenic impacts within the watershed. This new knowledge will help local stakeholders towards the recovery of a good geochemical and ecological status for the lagoon brackish water body of Biguglia.

How to cite: Crayol, E., Huneau, F., Garel, E., Re, V., Mattei, A., Santoni, S., and Pasqualini, V.: Socio-hydrogeological approach to identify contaminant fluxes towards groundwater-dependent hydrosystems, case of the Biguglia lagoon (Corsica, France), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3412, https://doi.org/10.5194/egusphere-egu22-3412, 2022.

Drinking water quality is a key component of water security to ensure clean and safe water supplies to achieve the Global SDG6. Yet frequently there are capacity constraints on the adequacy and sustained water quality monitoring programs in LDC contexts, especially in rural areas where resources are more limited and the resident population is more reliant on scattered independent groundwater supplies. In Malawi, knowledge of the importance of water quality has been developing over recent years, necessitating local capacity development for sufficient and sustained water quality monitoring.

International, transdisciplinary, and interdisciplinary research collaboration and capacity-building efforts in rural water quality monitoring can be a vehicle to improve technology development that supports operational monitoring and data reporting in resource-poor settings. However, in cognate fields, similar international partnership models have drawn some criticism of late, because of their alleged tendency to not translate collaboration agreements into demonstrable local capacity gains. We, therefore, link our consideration of these issues specific to our direct input to efforts to create a new water quality testing program in rural southern Malawi in southern Africa in a collaborative research project between the University of Dundee and Fisherman’s Rest, a local NGO in Malawi. Fisherman’s Rest works with rural communities in Malawi, specifically borehole monitoring under the Madzi Alipo program. However, their work lacked the water quality monitoring component, a key element to water security. Using our reflections, we find that the line of critique on international collaborations has some value in terms of thinking about how to advance ‘genuine’ collaboration and capacity-building in water quality monitoring programs as we look to expand our collaboration efforts with Fisherman’s Rest and other stakeholders in rural water quality monitoring in Malawi.

How to cite: Gomo, F., Halliday, S., Chichlowski, W., Chichloska, S., Zaunda, H., and Geddes, A.: Reflections on collaboration and capacity-building for sustainable groundwater quality monitoring in rural Malawi, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12846, https://doi.org/10.5194/egusphere-egu22-12846, 2022.

The Galápagos Archipelago (Ecuador) is traditionally considered a living museum and showcase of evolution. The rich biodiversity and distinctive environment attract thousands of visitors every year. However, this tourist flow exerts continuous pressures on the natural environment, and on water resources in particular, to the detriment of the local population who is faced with the challenges of accessing safe and sustainable drinking resources.

For this reason, over the years numerous projects, especially in the context of international cooperation activities, have tried to assess the impact of anthropogenic activities on the water quality and quantity in the islands. Unfortunately, the lack of coordination among all these projects did not allow to carry out continuous monitoring and, above all, to obtain homogenous and consistent time series of the measured hydrogeochemical parameters.

For this reason, in the framework of a joint technical cooperation project (“Health protection and prevention of anthropic pollution risks” in the Island of Santa Cruz” financed by Veneto Region, Italy; CS2012A19) a comprehensive assessment on water quality data (physico-chemical parameters, major elements, trace elements and coliforms) collected since 1985 in the Santa Cruz Island was performed. Results revealed the need of optimizing monitoring efforts to fill knowledge gaps and to better target decision making processes. All data were therefore standardized, homogenized and collected in an open database, accessible to all water stakeholders involved in water control, management and protection in the island. 

The information gathering activity also revealed the lack of coordination between the stakeholders themselves and the presence overlapping interests towards water resources, which represent an obstacle for coordinated actions targeted to sustainable water resources management in such a fragile environment. 

Therefore, under the guidance of the Santa Cruz Municipality, a Water Committee was established to foster the coordinated action among the water stakeholders in the island. The latter range from national to local authorities (e.g. National Water Secretariat, Ministry of Agriculture, Ecuador Naval Oceanographic Institute, National Park Galapagos, Municipality), research institutes (Charles Darwin Foundation), bottled water companies and Santa Cruz Households. Within the committee, shared procedures for data collection, sample analysis, evaluation and data assessment by an open access geodatabase were agreed collectively and tested in the field. Joint monitoring in the island can optimize the efforts for water quality assessment and protection, and improve accountability and outreach towards civil society and water users. Such a coordinated action can also ensure that international cooperation activities carried out in the island will respond to the real needs of the local population, and results will contribute to the long-term protection of the scarce water resources in the island.

Overall, results of the project revealed the high potential of adopting transdisciplinary approaches in complex, multi-stakeholder, framework typical of small island states.

How to cite: Tringali, C., Rizzi, J., Re, V., Tuci, C., Mancin, M., Mendieta, E., and Marcomini, A.: Insights from a transdisciplinary approach for water quality monitoring and multi-stakeholder management in the island of Santa Cruz, Galápagos (Ecuador), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4383, https://doi.org/10.5194/egusphere-egu22-4383, 2022.