The Chongwe River Catchment (CRC) is located in Zambia. It receives a mean annual precipitation of 889 mm. The catchment is facing growing anthropogenic and socio-economic activities leading to severe water shortages in recent years, particularly from July to October. The objective of this study was to assess the available water resources by investigating the important hydrological components and estimating the catchment water balance using the Water Evaluation and Planning (WEAP) model. The average precipitation over a 52 year period and a 34 year period of streamflow measurement data for four stations were used in the hydrological balance model. The results revealed that the catchment received an estimated mean annual precipitation of 4603.12 Mm3. It also released an estimated mean annual runoff and evapotranspiration of 321.94 Mm3 and 4063.69 Mm3, respectively. The estimated mean annual total abstractions in the catchment was 119.87 Mm3. The average annual change in the catchment storage was 120.18 Mm3. The study also determined an external inflow of 22.55 Mm3 from the Kafue River catchment. The simulated mean monthly streamflow at the outlet of the CRC was 10.32 m3/s. The estimated minimum and maximum streamflow volume of the Chongwe River was about 1.01 Mm3 in September and 79.7 Mm3 in February, respectively. The performance of the WEAP model simulation was assessed statistically using the coefficient of determination (R2 = 0.97) and the Nash–Sutcliffe model efficiency coefficient (NSE = 0.64). The R2 and NSE values indicated a satisfactory model fit and result. Meeting the water demand of the growing population and associated socio-economic development activities in the CRC is possible but requires appropriate water resource management options.

Chongwe River Catchment, a sub-catchment of the Zambezi River Basin, has been experiencing changes in land use/land cover (LULC) and in its hydrology. This study aims to assess the impact of LULC changes on the catchment's hydrological components such as streamflow, evapotranspiration and water abstractions. LULC change data, detected from the 1984, 1994, 2014 and 2017 USGS Landsat imagery using a maximum likelihood supervised classifier, were integrated into the WEAP Model along with soil, slope and hydro-climate data. The results showed that between 1984 and 2017 built-up area increased by 382.77% at 6.97 km 2 /year, irrigated agriculture increased by 745.62% at 1.70 km 2 /year, rainfed farms/ranch/grassland increased by 14.67% at 14.53 km 2 /year, forest land decreased by 41.11% at 22.33 km 2 /year and waterbodies decreased by 73.95% at 0.87 km 2 /year. Streamflow increased at a rate of 0.13 Mm 3 per annum in the wet seasons and showed a high variation with flow volume of 79.68 Mm 3 in February and 1.01 Mm 3 in September. Annual actual evapotranspiration decreased from 840.6 mm to 796.3 mm while annual water abstraction increased from 8.94 mm to 23.2 mm from the year 1984 to 2017. The pattern of LULC change between 1984 and 2017 has negatively impacted the hydrology of the Chongwe River Catchment. From these findings, an integrated catchment management and protection approach is proposed to mitigate the negative impacts of LULC dynamics on hydrological components in the Chongwe River Catchment.Sustainability 2019, 11, 6415 2 of 13 rainfall to water yield through altering an ecosystem's hydrological characteristics such as infiltration, evapotranspiration, and groundwater recharge capacity [7]. Understanding the impact of LULC change on watershed hydrology at catchment level could help to (i) identify and alleviate the occurrence of critical shifts in hydrologic processes, (ii) assess the water resources availability and their sustainable utilization under increasing population, agricultural expansion, and industrialization, and (iii) formulate appropriate policies to improve land use planning and spatial developments [8][9][10]. In this regard, direct field observations and spatial-temporal analysis of LULC change from remote sensing data play a crucial role in providing historical and current information to understand the effects on river ecosystem, guide urban densification and limit unsustainable urban expansion at catchment level [11][12][13].The Chongwe River Catchment, with a population of over 834,359 people, is a sub-catchment of the Zambezi River Basin [14,15], and has been experiencing changes in LULC influenced by the fast-growing population, infrastructure and social-economic developments particularly in Lusaka City [15][16][17]. About 45% of Lusaka City falls within the Chongwe River Catchment [16]. The majority of the people in the catchment depend on the Chongwe River and its main tributaries for their domestic, agriculture, industrial and socio-economic water needs. The demand for water has dra...

Flood‐based farming is a means of improving crop production in rain‐deficit lowlands. Such spate irrigation systems are growing in importance, although the effects of headwater hydrological deficit on downstream flood farming are lacking evidence. This study investigates the impacts of headwater hydrological deficit on the extent of spate‐irrigated agriculture in the Guguf spate system. The length of canals and area of spate‐irrigated agriculture to the right and left of the Guguf River for the 1980s and 2010s were tracked using a global positioning system and mapped in a geographic information system interface, while climate data were collected from National Meteorological Agency. Trends of selected hydroclimatic variables were analysed using linear regression and the Pettitt test. The flash floods have shrunk by 7.36 × 106 m3, as a result of which the length of canals and area of spate‐based farms declined by 1.37 km and 1540 ha, i.e. 35 and 57.5%, respectively, in only three decades. This corresponds to an average withdrawal of −44.0 ha yr‾¹. A single 1 million m3 decline in flash floods caused a 366.4 ha decline in spate‐based farms. Moreover, farm fields located next to the river course are less affected, compared to those at the tail of the scheme. If the current trend continues, there is a high risk that the remaining farms currently receiving floods may find themselves outside of the spate systems. Therefore, we suggest that flood management technologies are needed to optimize the efficiency of soil moisture in the spate system. © 2020 John Wiley & Sons, Ltd.

Ngwerere and Kanakatampa Streams are the main tributaries of the Chongwe River. The Ngwerere stream originates from the city of Lusaka and meanders through Lusaka City and Chongwe Town for an approximate distance of 41 km before joining into the upper part of Chongwe River. The Kanakatampa Stream is a tributary of the Chongwe River. It meanders from the Kanakatampa Area for approximately 52 km before discharging into the middle of the upper part of the Chongwe River. The Chongwe River Catchment which is a sub-catchment of the Zambezi Basin drew the attention of researchers and policymakers when the Chongwe River started drying up in the dry seasons causing a water crisis particularly in the downstream regions of the middle catchment. Therefore, it is important from the water resources management perspective, to assess the contribution of tributaries into the flows of the Chongwe River. Ngwerere and Kanakatampa streams are socially, economically, and environmentally important streams for the city of Lusaka and surrounding area. This study, therefore, concentrated on evaluating the flow contribution of the two streams to the Chongwe River using the Water Evaluation And Planning (WEAP) tool. The streamflow data recorded at the Chongwe Great East Road Bridge gauging station were used in the WEAP embedded Parameter ESTimation (PEST) auto-calibration tool to calibrate (1970-1999) and validate (2000-2010) the model. The monthly streamflow model calibration and validation results were assessed using the How to cite this paper:

The Chongwe River Catchment (CRC) is located in Zambia. It receives a mean annual precipitation of 889 mm. The catchment is facing growing anthropogenic and socio-economic activities leading to severe water shortages in recent years, particularly from July to October. The objective of this study was to assess the available water resources by investigating the important hydrological components and estimating the catchment water balance using the Water Evaluation and Planning (WEAP) model. The average precipitation over a 52 year period and a 34 year period of streamflow measurement data for four stations were used in the hydrological balance model. The results revealed that the catchment received an estimated mean annual precipitation of 4603.12 Mm 3 . It also released an estimated mean annual runoff and evapotranspiration of 321.94 Mm 3 and 4063.69 Mm 3 , respectively. The estimated mean annual total abstractions in the catchment was 119.87 Mm 3 . The average annual change in the catchment storage was 120.18 Mm 3 . The study also determined an external inflow of 22.55 Mm 3 from the Kafue River catchment. The simulated mean monthly streamflow at the outlet of the CRC was 10.32 m 3 /s. The estimated minimum and maximum streamflow volume of the Chongwe River was about 1.01 Mm 3 in September and 79.7 Mm 3 in February, respectively. The performance of the WEAP model simulation was assessed statistically using the coefficient of determination (R 2 = 0.97) and the Nash-Sutcliffe model efficiency coefficient (NSE = 0.64). The R 2 and NSE values indicated a satisfactory model fit and result. Meeting the water demand of the growing population and associated socioeconomic development activities in the CRC is possible but requires appropriate water resource management options.