Hydrological and water resources modelling under uncertainty and climate change: An application to the Limpopo basin, Botswana

The application of water resources planning models to semi-arid or arid areas is expected to be particularly challenging because of the high variability of rainfall and streamflow, highly limited historic observations, sparse rain gauge and flow networks with significant periods of missing rainfall and potential data quality issues. These lead to high uncertainty in rainfall and hydrological models which need to be explicitly represented in model predictions. These uncertainties are expected to increase when considering future predictions associated with the effects of climate change. This has presented an opportunity for this thesis to develop a framework of uncertainty analysis in hydrological and water resources modelling. The framework consists of multi-site continuous time stochastic rainfall model to (1) identify suitable rainfall predictors, (2) infill the missing values in the historic rainfall data, (3) extend the limited rainfall observations, and (4) generate rainfall under climate change scenarios by downscaling global climate models outputs. The stochastically infilled rainfall data allows calibration of a hydrological model under input uncertainty. The rainfall model together with the uncertain hydrological model are then used to generate multiple realisations of reservoir inflows over a 100-year period, first assuming a stationary climate and secondly under a changed climate. This framework is applied to the upper Limpopo basin in Botswana, using 25 years of observed daily rainfall and flow data for model calibration. A Generalised Linear Model was used for the rainfall and a semi-distributed version of the IHACRES model was used for the hydrology. A proposed 382 Mm3 reservoir at the outlet of this basin, which is part of Botswana‘s national water resource strategy, is re-evaluated in light of the extended inflow data and the estimated uncertainty. Analysis within this thesis revealed that the effects of data and model parameter uncertainty on water resources planning models can be high, and thus should not be ignored. The thesis advocates a shift from deterministic to stochastic ways of infilling missing rainfall values, and for consideration of hydrological model uncertainty, climate model and climate scenario uncertainties. Given the high uncertainty in the semi arid case study, priority areas can be identified, which may include acquiring and expanding the gauge networks, building efficient and robust data collection processing and achieving to improve the existing database so as to support and enable quality research

Assessing the Effects of LULC Change on Landslide Hazards in Rwanda: A Case Study in Nyabihu District

Landslides have become important environmental hazard in hilly regions of Rwanda such as Nyabihu district. They are characterized by the downslope movement of debris or other earth materials which damage or destroy everything found in their way such as infrastructure, croplands, and even cause a number of human deaths. The main triggering factors of landslides in Rwanda are intense rainfall and land use/land cover (LULC) change. Therefore, the objective of this study was to assess the LULC change effects on landslide occurrences. LULC maps of 2005 and 2015 were generated and overlaid with mapped landslides. Maximum likelihood classification was used to classify the Landsat satellite images. The results revealed a remarkable decrease of agricultural land, while all other LULC types have increased in the studied period. It was noted that most of the landslides occurred in agricultural land. The study results are expected to be useful for landslide hazard management decisions, land use planning and management regulations, so as to minimize the likelihood of landslide occurrences and their resultant impacts

Assessing the effects of LULC change on landslide hazards in Rwanda : a case study in Nyabihu district

Landslides have become important environmental hazard in hilly regions of Rwanda such as Nyabihu district. They are characterized by the downslope movement of debris or other earth materials which damage or destroy everything found in their way such as infrastructure, croplands, and even cause a number of human deaths. The main triggering factors of landslides in Rwanda are intense rainfall and land use/land cover (LULC) change. Therefore, the objective of this study was to assess the LULC change effects on landslide occurrences. LULC maps of 2005 and 2015 were generated and overlaid with mapped landslides. Maximum likelihood classification was used to classify the Landsat satellite images. The results revealed a remarkable decrease of agricultural land, while all other LULC types have increased in the studied period. It was noted that most of the landslides occurred in agricultural land. The study results are expected to be useful for landslide hazard management decisions, land use planning and management regulations, so as to minimize the likelihood of landslide occurrences and their resultant impacts

Using ICT tools to promote the governance of groundwater resources in semi-arid areas of Southern Africa: the Stampriet Transboundary Aquifer System

Central Namibia, Western Botswana, Northern Cape Province, water security, FREEWAT, modellin

The SASSCAL contribution to climate observation, climate data management and data rescue in Southern Africa

A major task of the newly established "Southern African Science Service Centre for Climate Change and Adaptive Land Management" (SASSCAL; www.sasscal.org) and its partners is to provide science-based environmental information and knowledge which includes the provision of consistent and reliable climate data for Southern Africa. Hence, SASSCAL, in close cooperation with the national weather authorities of Angola, Botswana, Germany and Zambia as well as partner institutions in Namibia and South Africa, supports the extension of the regional meteorological observation network and the improvement of the climate archives at national level. With the ongoing rehabilitation of existing weather stations and the new installation of fully automated weather stations (AWS), altogether 105 AWS currently provide a set of climate variables at 15, 30 and 60 min intervals respectively. These records are made available through the SASSCAL WeatherNet, an online platform providing near-real time data as well as various statistics and graphics, all in open access. This effort is complemented by the harmonization and improvement of climate data management concepts at the national weather authorities, capacity building activities and an extension of the data bases with historical climate data which are still available from different sources. These activities are performed through cooperation between regional and German institutions and will provide important information for climate service related activities

Resilience in the Limpopo Basin : The potential role of the transboundary Ramotswa aquifer - Baseline report

The overall objective of the RAMOTSWA project is to support a long-term joined vision and cooperation on the shared groundwater resources of the Upper Limpopo region, where the states share significant and valuable underground freshwater resources as well as space for enhanced subsurface water storage. The project will facilitate and promote joint management and better groundwater governance focused on coordination, scientific knowledge, social redress and environmental sustainability, in order to reduce poverty and inequity, increase prosperity, and improve livelihoods and water and food security in the face of climate change and variability

Resilience in the Limpopo Basin : The potential role of the transboundary Raotswa aquifer - Final draft

As complementary report of the baseline report, this report focus on the hydrogeological assessment of the Ramotswa Transboundary Aquifer and covers only aspects related to the biophysical conditions of the aquifer which is a karstic dolomit aquife straddling the international border between Botswana and South Africa. The assessment is based on existing data and field data collected (including Airborne Electro-Magnetic survey) during the period September 2015 –November 2016. The technical knowledge developed in the report will be used as based for developing tools for harmonized management and fostering crossborder dialogue in order to help building the joint Strategic Action Programme which will provide, not exclusively, guidelines for better monitoring and future assessment of the aquifer

A rainfall model for drought risk analysis in south-east UK

Drought risk assessment ideally requires long-term rainfall records especially where inter-annual droughts are of potential concern, and spatially consistent estimates of rainfall to support regional and inter-regional scale assessments. This paper addresses these challenges by developing a spatially consistent stochastic model of monthly rainfall for south-east UK. Conditioned on 50 gauged sites, the model infills the historic record from 1855-2011 in both space and time, and extends the record by synthesising droughts which are consistent with the observed rainfall statistics. The long record length allows more insight into the variability of rainfall and potentially a stronger basis for risk assessment than is generally possible. It is shown that, although localised biases exist in both space and time, the model results are generally consistent with the observed record including for a range of inter-annual droughts and spatial statistics. Simulations show that some of the most severe inter-annual droughts on the record may recur, despite a trend towards generally wetter winters