Browsing by Author "Mul, Marloes"

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Comparison of blue and green water fluxes for different land use classes in a semi-arid cultivated catchment using remote sensing
(Elsevier, 2021-08) Msigwa, Anna; Komakech, Hans; Salvadore, Elga; Seyoum, Solomon; Mul, Marloes; van Griensven, Ann
Study area Kikuletwa catchment, Upper Pangani River Basin, Tanzania. Study focus This study compared yearly blue and green water fluxes using four different methods: Senay’s method (SN) (Senay et al., 2016), van Eekelen method (EK) (van Eekelen et al., 2015), the Budyko method (Simons et al., 2020) and the Soil Water Balance (SWB) model (FAO and IHE Delft, 2019). The yearly blue and green water fluxes of different Land Use Land Cover (LULC) classes were estimated using an ensemble of seven global remote sensing-based evapotranspiration products (Ensemble ET) and the CHIRPS rainfall dataset. The Ensemble ET was created from seven global RS-based surface energy balance models (GLEAM, CMRS-ET, SSEBop, ALEXI, SEBS, ETMonitor and MOD16). New hydrological insights Our study found that the EK method was able to map blue and green water fluxes with realistic results for irrigated and non-irrigation cultivated areas. Budyko and SWB gave too high blue water fluxes for the non-irrigated agricultural areas, whereas the Budyko and SWB models were not able to show a clear difference in blue-water fluxes in irrigated versus non-irrigated areas. On the other hand, the SN method estimated no blue water fluxes in more than half of the identified irrigated areas. Three of the four methods estimate the highest blue water fluxes (318–582 mm/y) in forested areas, while the SWB model estimates the highest blue water fluxes in irrigated banana and coffee (278 mm/y). Overall, we conclude that the EK method yielded the most realistic spatial pattern of blue-water fluxes when compared to the irrigated land use map, whereas SWB could be considered after further calibration if higher temporal data resolution (e.g. monthly) is required.
Formalization of water allocation systems and impacts on local practices in the Hingilili sub-catchment, Tanzania
(Taylor & Francis online, 2013-05-31) Komakech, Hans; van der Zaag, Pieter; Mul, Marloes; Mwakalukwa, Tulinumpoki; Kemerink, Jeltsje
Water scarcity caused by increased demands often leads to competition and conflict over water in many river catchments in Sub-Saharan Africa. At the local level, water users have in many places been able to solve water allocation problems by crafting institutions based on customs and traditions. These self-governing arrangements are not necessarily fair or good, but are able to adapt to the changing resource context. Simultaneously, many African governments have adopted new policies and laws, and established new institutions to achieve equitable and sustainable management of water resources. The formalization of the property right to water is often part of the recipe. This paper analyses the impact of one such government-led formalization process on local water allocation practices. Based on a field study in the Hingilili sub-catchment, Tanzania, we find that government interventions do not achieve the goal of equitable and sustainable water management. However, we find that the principle of good neighbourhood that still exists between the highland and lowland farmers in Hingilili could form a base to reconcile diverging water interests between the highland and lowland farmers. The paper shows that the concept of bricolage [Cleaver, F., 2002. Reinventing institutions: bricolage and the social embeddedness of natural resource management. The European Journal of Development Research, 14 (2), 11–30] is useful to demonstrate the need for new institutions to be sufficiently embedded in existing local practices to succeed, but this is not a sufficient condition. The hydraulic position of the various actors (upstream or downstream) must also be taken into account, and may be considered a driver for institutional innovation.
Water allocation and management in an emerging spate irrigation system in Makanya catchment, Tanzania
(Elsevier, 2011-09) Komakech, Hans; Mul, Marloes; van der Zaag, Pieter; Rwehumbiza, Filbert
Although spate irrigation systems are risk-prone, they can be an important component for livelihood security in semi-arid areas. Spate uses water (flood water), which upstream users often do not require, as rainfall during these periods is more than sufficient. The use of this flood water for spate irrigation is therefore a good opportunity to convert water with a low opportunity cost to high value water. As more rivers are closing, due to socio-economic and climate changes, spate irrigation may become increasingly relevant in semi-arid areas. Spate irrigation systems pose institutional and technical challenges: collective action is challenged by complex upstream–downstream interactions between users within the system, and the high labour demands for regular reconstruction of temporary diversion weirs and intake structures. This paper describes a spate irrigation system in Makanya village, Tanzania that emerged in response to increased upstream water use. We use three of the four dimensions (hydrological, hydraulic and sociological) of spate irrigation proposed by Van Steenbergen (1997) to assess the Makanya spate irrigation system. The Makanya spate irrigation system has an organisational structure that is similar to the canal irrigation (furrow) committees located upstream, and effectively deals with the institutional demands of managing water in spate irrigation systems. Water allocation is reminiscent to the water sharing arrangements existing in the full irrigation system, which previously was in place at the site and in the high- and midlands of the Makanya catchment and therefore set this system apart from the traditional spate irrigation practice elsewhere. Technically, a major challenge is the reconstruction of the head works after each flood. Another aspect is the changes in the river bed. Flash floods carry sediments that deposit on the fields, raising the elevation of the irrigated land every year and making it increasingly difficult for the river water to enter the plots. Improving system efficiency through modernisation of the diversion and distribution structures in this case is not feasible due to the huge amounts of sediments delivered to the system each year. Instead investments in conjunctive use of groundwater could be the solution because it involves a relatively small intervention, minimises the physical disturbance of the system, and therefore is likely to respect the existing locally developed water management arrangements.