## 4 Discussion
### Integrated Water Resource Management (IWRM) Recommendations  
IWRM recommendations are made based on the paleo-geohydroology control (Figure 15). These should inform policy revision for delivery of improved water supply security and are primarily outcomes from understanding the significance of the paleo-lake environment on basin groundwater quality. Recommendations are cross referenced to the Figure 15 conceptual model (as labels [a] to [f]) with application geared to the Phalombe District circumstance, but set within the wider Chilwa Basin context. They are conditioned by our parallel assessment of water point functionality and current asset status (Figures 13 and 14). Recommendations are as follows. 1. Development and investment (incl. water point repair where justifiable) of the low-TDS groundwater and streams in the basin uplands, especially at points above the high-level deposits demarcation line as these offer the best long-term prospect of low-TDS good-quality supply (Figure 15, label [a]). Development of groundwater sources needs to be cognisant of iron (and manganese) issues. 2. General avoidance and curtailing of community drinking water supplies from most groundwater that is confined or semi-confined by the high-level and particularly lake terrace deposits; although some groundwater may meet less stringent Malawian standard, most would breach the WHO threshold for brackish water ideally met for drinking water supply (label [b]). 3. Development, of low-TDS groundwater in the lowland lake terrace areas where this (i) locally occurs within aquifer units recharged by infiltration of low-TDS river-water (label [c]), or (ii) exists in former river channel fluvial sand and gravels deposits at depth, e.g., towards the study area north-west--Phalombe estuary area (label [d]). 4. Increased protection of flows and quality of low-TDS upland groundwater and stream sources, especially by the careful location of agricultural activity and sanitation facilities ensuring adequate standoff from streams and boreholes. Appropriate aforestation to address run off versus recharge in-balance (label [e]). Similar protection is recommended for lowland lake terrace area, recognising the protection or river flows, quality and suspended sediment contents will be primarily driven by Lake Chilwa protection and secondly groundwater. 5. Development of robust, properly maintained low-TDS stream/river-water supplies, in particular more resilient gravity-fed water supply schemes using upland perennial source streams with water offtakes that pipe supply to greater population numbers (label [f]). 6. Lake basin catchments are inherently complex due to the need to manage groundwater, a stream/river network and the lake itself, IWRM in conjunction with sympathetic land management needs to be carefully practiced to maintain water supplies, safeguard resource and protect the lake and wider basin environment and land use. This includes the adequate collection of water use data to inform water balances and allow its equitable management. 7. Continued proactive development of the system conceptual model developed herein. Concerning the last two items, although our focus has mostly been on groundwater, and despite the failings of past gravity-fed water supply schemes attributed largely to poor maintenance, a key recommendation is for the further development of gravity-fed water supply schemes--especially larger capacity schemes that are managed in a professional manner and which are able to serve greater population numbers (with suitable appropriation or decommissioning of failing infrastructure). The Gov't of Malawi with funds from the AfDB is rehabilitating two large gravity-fed water supply scheme in Phalombe District, the 'Phalombe Major' and 'Sombani Weir' schemes located high in the catchment foothills, within area of low-TDS river water and groundwater (Figure S17).