Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

Hamer, W. de; Love, David W.; Owen, Richard; Booij, Martijn J.

doi:10.1016/j.pce.2008.06.056

Cited by 25 publications

(14 citation statements)

References 12 publications

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“…The agricultural water supply capacity of a reservoir is typically determined based on the available supply, and accounts for water inflow into the basin in the reservoir, water supply by the irrigation facilities and water demand of the irrigated districts. For more accurate estimation of irrigation water supply and demand, reservoir operation and irrigation water demand are often estimated using the water balance concept [46,47]. Three sets of constraints were considered for this study: the water balance of a reservoir based on evaporation loss, the limitations on available water and the restrictions imposed based on the reservoir capacity.…”

Section: Water Resources Balance Model For Reservoirsmentioning

confidence: 99%

Regional Climate Change Impacts on Irrigation Vulnerable Season Shifts in Agricultural Water Availability for South Korea

Nam

Kim

Hong

et al. 2017

Water

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Abstract:Reservoirs are principal water resources that supply irrigation water to paddy fields and play an important role in water resources management in South Korea. For optimal irrigation reservoir operation and management, it is necessary to determine the duration of irrigation water shortages. Management of reservoir operation and irrigation scheduling should take into consideration essential variables that include the water supply in a reservoir and the water demand in the associated irrigation district. The agricultural water supply and demand show different patterns based on the variability and uncertainty of meteorological and hydrological phenomena. The duration of excessive water supply can be quantitatively determined through analysis of deviations and changes in the timing of agricultural water supply and demand. In this study, we introduce an approach to assess the vulnerable seasons of paddy irrigation to enable more effective operation and management of reservoirs. The vulnerable seasons were evaluated through comparison of the potential water supply capacity and irrigation water requirements based on water budget analysis via a time series change analysis. We have assessed the changing in the total duration and duration shifts of the vulnerable irrigation seasons for four agricultural reservoirs using past observed data from meteorological stations maintained by the Korea Meteorological Administration (KMA) and projected climate change scenarios (2011-2100) as depicted by the Representative Concentration Pathways (RCPs) emission scenarios. For irrigation vulnerable seasons under both the RCP 4.5 and RCP 8.5 scenarios, the results showed periods of significant increases in which total vulnerable seasons compared to the historical period; the longest duration of vulnerability occurred during the 2071-2100 period under the RCP 8.5. Identification of the vulnerable seasons for paddy irrigation can be applied in agricultural water management to more effectively manage reservoir operation during irrigation periods with climate changes.

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Section: Water Resources Balance Model For Reservoirsmentioning

confidence: 99%

Regional Climate Change Impacts on Irrigation Vulnerable Season Shifts in Agricultural Water Availability for South Korea

Nam

Kim

Hong

et al. 2017

Water

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“…Governments in some countries for example Tanzania and South Africa have also gone a step further in decentralizing irrigation management by promoting farmer managed irrigation schemes so as to ensure effective management of community based land and water resources (van Koppen et al, 2004;Mudau, 2010). Irrigation is viewed as a mechanism for reducing the impact of climate change and climate variability (IPCC, 2007;Ncube et al, 2011;Chikozho, 2010;de Hamer et al, 2008;Love et al, 2006;Van der Zaag et al, 2010).…”

Section: Decentralizationmentioning

confidence: 99%

Decentralising Zimbabwe’s water management: The case of Guyu-Chelesa irrigation scheme

Tambudzai

Mapedza

Zhou

2013

Physics and Chemistry of the Earth, Parts A/B/C

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a b s t r a c tSmallholder irrigation schemes are largely supply driven such that they exclude the beneficiaries on the management decisions and the choice of the irrigation schemes that would best suit their local needs. It is against this background that the decentralisation framework and the Dublin Principles on Integrated Water Resource Management (IWRM) emphasise the need for a participatory approach to water management. The Zimbabwean government has gone a step further in decentralising the management of irrigation schemes, that is promoting farmer managed irrigation schemes so as to ensure effective management of scarce community based land and water resources. The study set to investigate the way in which the Guyu-Chelesa irrigation scheme is managed with specific emphasis on the role of the Irrigation Management Committee (IMC), the level of accountability and the powers devolved to the IMC. Merrey's 2008 critique of IWRM also informs this study which views irrigation as going beyond infrastructure by looking at how institutions and decision making processes play out at various levels including at the irrigation scheme level. The study was positioned on the hypothesis that 'decentralised or autonomous irrigation management enhances the sustainability and effectiveness of irrigation schemes'. To validate or falsify the stated hypothesis, data was gathered using desk research in the form of reviewing articles, documents from within the scheme and field research in the form of questionnaire surveys, key informant interviews and field observation. The Statistical Package for Social Sciences was used to analyse data quantitatively, whilst content analysis was utilised to analyse qualitative data whereby data was analysed thematically. Comparative analysis was carried out as Guyu-Chelesa irrigation scheme was compared with other smallholder irrigation scheme's experiences within Zimbabwe and the Sub Saharan African region at large. The findings were that whilst the scheme is a model of a decentralised entity whose importance lies at improving food security and employment creation within the community, it falls short in representing a downwardly accountable decentralised irrigation scheme. The scheme is faced with various challenges which include its operation which is below capacity utilisation, absence of specialised technical human personnel to address infrastructural breakdowns, uneven distribution of water pressure, incapacitated Irrigation Management Committee (IMC), absence of a locally legitimate constitution, compromised beneficiary participation and unclear lines of communication between various institutions involved in water management. Understanding decentralization is important since one of the key tenets of IWRM is stakeholder participation which the decentralization framework interrogates.

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“…Aerts et al, 2007) and minimize downstream groundwater flow when constructed subsurface (e.g. De Hamer et al, 2008).Recharge of the aquifers by managed releases from an upstream dam also increases the year-round availability of alluvial groundwater ).…”

Section: The Potential Of Alluvial Aquifers In Ephemeral Riversmentioning

confidence: 99%

“…In some geological environments, especially in younger crystalline rock terrains, the bedrock is impermeable and seepage from the aquifer is negligible: stream channels tend to erode and remove weathered regolith, leaving fresh, less permeable bedrock at the base of the sandbed. However, in older, more deeply-weathered terrains, seepage can be a substantial flux (De Hamer et al, 2008); it is best estimated by monitoring water level declines during periods when Q in,s and Q abs are zero. Groundwater outflow only occurs where there is another alluvial aquifer block immediately downstream of the one being studied and surface water outflow only occurs when the aquifer is fully saturated.…”

mentioning

confidence: 99%

A water balance modelling approach to optimising the use of water resources in ephemeral sand rivers

Love¹,

Zaag

Uhlenbrook

et al. 2011

River Research & Apps

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Alluvial aquifers present a possibility for conjunctive use with surface reservoirs for the storage of water in ephemeral sand rivers such as the Mzingwane River in the Limpopo Basin, Zimbabwe. The Lower Mzingwane valley is a semi-arid region with high water stress, where livelihoods have revolved around the large rivers for thousands of years. However, current water allocation favours the commercial user: of the 2600 ha irrigated in the 5960 km 2 (596 000 ha) region, only 410 ha are for smallholder farmers. A water balance approach was used to model the surface water resources and groundwater resources to determine the potential for expanding irrigation and to explore water allocation options. Using a combination of field and laboratory investigations, remote sensing and existing data, the Lower Mzingwane valley was modelled successfully using the spreadsheet-based model WAFLEX, with a new module incorporated to compute the water balance of alluvial aquifer blocks.Results showed that the Lower Mzingwane alluvial aquifers can store 38 Â 10 6 m 3 of water, most of that storage being beyond the reach of evaporation. Current water usage can be more than tripled: the catchment could supply water for currently-planned irrigation schemes (an additional 1250 ha), and the further irrigation of two strips of land along each bank of the Mzingwane River (an extra 3630 ha)-without construction of any new reservoirs. The system of irrigating strips of land along each bank of the Mzingwane River would be decentralized, farmer or family owned and operated and the benefits would have the potential to reach a much larger proportion of the population than is currently served. However, there could be substantial downstream impact, with around nearly onethird of inflows not being released to the Limpopo River.The approach developed in this paper can be applied to evaluate the potential of alluvial aquifers, which are widespread in many parts of semi-arid Africa, for providing distributed access to shallow groundwater in an efficient way. This can enhance local livelihoods and regional food security.

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Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

Cited by 25 publications

References 12 publications

Regional Climate Change Impacts on Irrigation Vulnerable Season Shifts in Agricultural Water Availability for South Korea

Regional Climate Change Impacts on Irrigation Vulnerable Season Shifts in Agricultural Water Availability for South Korea

Decentralising Zimbabwe’s water management: The case of Guyu-Chelesa irrigation scheme

A water balance modelling approach to optimising the use of water resources in ephemeral sand rivers

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