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In arid areas, water diverted from highly uncertain flash floods is often the only source of water for crop production. Stakeholders in spate irrigation systems have developed numerous measures to cope with uncertain water supply related to low, high and untimely floods. This research evaluates the effectiveness of these measures using the MULINO Decision Support System (mDSS4) tool which is based on the Driving force-PressureState-Impact-Response (DPSIR) framework. Using data from interviews with 101 randomly selected farmers, 17 water user associations (WUAs), and 7 system water managers in the Gash spate irrigation system in Sudan, we compare the effectiveness with the rate of adoption. The results reveal the most effective measures are 1) pre-flood preparedness, 2) risk sharing measures through water and land management during and after flood by WUAs, 3) crop management by farmers; and 4) flexibility in operation by water managers. Unfortunately, the most effective measures are not the most adopted ones. The level of adoption is primarily related to the capacity of the farmers, WUAs and water managers to implement the measures without outside support. Generally, measures taken by downstream farmers are less effective than those adopted by upstream farmers due to weak institutional arrangements and lack of adequate resources. Supporting farmers, WUAs and water managers for a wider adoption of the existing effective measures will greatly improve irrigation performance and hence food security in the study area.