Addressing the silo mentality in the water sector - Modelling connections between WASH (Water, Sanitation and Hygiene) and Hydrology, in the case of the Tupiza watershed, in Bolivia

Abstract:

Water management and sanitation services are a serious challenge in Bolivia. The drought of 2017 resulted in a water supply crisis and was followed by widespread flooding in 2018. To date, access to safely managed sanitation services is limited, especially in the rural areas, and less than 15% of the wastewater receives any treatment. Integrated Water Resources Management (IWRM) rarely accounts for the influence of potential development in the Water, Sanitation and Hygiene (WASH) sector. Similarly, WASH investments seldom consider the impacts at the watershed scale. There is a missing link between IWRM and WASH that prevents a holistic approach to water management. Our study presents a quantitative model of this link. A WASH component was added to an existing biophysical watershed model of the Tupiza River system, in Southern Bolivia. WASH data was obtained from the survey of 312 households in the Tupiza watershed and supplemented with secondary sources (e.g. Census data). It was found that in the rural area 25% of the households have access to a safely managed water service compared with 52% in the urban area. In terms of sanitation, the contrast is even more striking with 81% of the urban population and only 4% of the rural population connected to a safely managed service. Results show that beyond water availability, water consumption highly depends on access to a water distribution network. Other factors such as the distance to a water source and the type of sanitation infrastructure also play a role. Moreover, wastewater generation is strongly driven by water consumption. The results suggest that WASH development is needed in Tupiza but expanding piped systems may put pressure on the watershed. Therefore, alternatives focusing on sustainable sanitation and efficient water use should be explored with the local communities. Some uncertainties such as a water demand increase during the COVID-19 pandemic may put additional stress on the watershed. By simulating the connections between WASH and IWRM, our model is a first step towards supporting decision-making that is sound for both sectors. As it represents different scales of intervention, this model could be used to evaluate water management strategies under different scenarios together with water managers and local communities.