Decision Support System for Runoff Water Harvesting and Irrigation
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Date
2016
Authors
Singa, Darwin Dodoma
Tumbo, Siza Donald
Fatael, Mahoo Henry
Filbert, Rwehumbiza
Maxon, Lowole
Journal Title
Journal ISSN
Volume Title
Publisher
Science Domain
Abstract
Despite the prevailing versatility of agro-hydrological Decision Support Systems (DSS) in the
agricultural sector, a number of associated deficiencies do exist. The deficiencies are due to lack of
synchronization of runoff affecting rainfall, catchment factors, reservoir capacity and irrigation field
area in the face of recurring droughts and dry spells in several areas of Sub-Saharan Africa (SSA).
The study focused on designing and validating a Decision Support System, by adding water
reservoir and irrigation sub-routines to an Agro-hydrological Nedbor Afstromnings Model (NAM) to
assist in screening best-bet options for either crop field area or reservoir size using a case study of common beans (Phaseolus vulgaris, L.) at Ukwe Area in Malawi. Microsoft excel spreadsheet (MS
excel) was used to compute cumulative runoff inflows into the dam, seasonal open surface water
storage, water losses and withdrawal and reservoir water available for the bean crop. Computer
simulation using soil, vegetation and topographical characteristics, and crop water requirements
revealed proportion of catchment to irrigation command area of 10:1 with bean water productivity of
0.7 g/l (0.7 kg/m3
), indicating low water demand. The NAM simulated values were in agreement
with calculated ones. Post-DSS gross margin analysis indicated that 2.42 times more crop returns
were obtained from irrigated than rain-fed bean crops despite additional costs associated with
reservoir maintenance and irrigation operations. The DSS is, hence, found potential for users in
drought prone Sub-Saharan African countries such as Malawi.
Description
Journal Article
Keywords
Irrigation, Reservoir, Runoff, Simulation, Storage, Synchronization