Multi-Criteria Analysis Of Drought Monitoring And Assessment In Sudan Based On Remote Sensing And GIS Technology

The monitoring meteorological and hydrological droughts is very important and significant for the most developing countries whose economic sustainability is strongly based on agriculture sector.Drought monitoring and prediction have been required for large impact on crop productivity and runoff.In Sudan,the occurrence of drought events is a predominant natural disaster that causes substantial damages to crop production and decrease the rivers discharge.The main aims of this study were to monitor drought and measure its impact on the crop yield and rivers discharge based on remote sensing and GIS technology.Currently,the high-resolution satellite images and interpolated data sets in near realtime have gained more popularity for natural disaster detection due to the unavailability and difficulty of acquiring frequent ground observation data over a wide region.In this study,several data sets were used including;MOD 13A3 for vegetation,MOD 16A2 for evapotranspiration,TRMM precipitation products 3B43,CRU TS for precipitation,temperature and ground observation measurements(meteorological and runoff data).The present study focused on assessing and analyzing meteorological and hydrological droughts characteristics using multi-criteria(Severity,Periodicity and Areal extent)analyses utilizing four drought indices,namely the Standardized Precipitation Index(SPI),the Drought Severity Index(DSI),the Standardized Evapotranspiration Index(SPEI)and Standardized Runoff Index(SRI),and inferred the impact of drought on sorghum productivity in Sudan from 2001 to 2011.The wavelet transform(WT)was used to study the relation between the meteorological and hydrological droughts in the Atbara River basin.To identify the wet and dry areas,the deviations of tropical rainfall measuring mission(TRMM)precipitation products from the long-term mean from 2001 to 2011 were computed and mapped at a seasonal scale(July–October).It is significant to study the impacts of meteorological droughts on the hydrological drought,which assist to detect drought propagation process,there by being useful for drought mitigation.In this study,we used long-term(1971–2011)hydrometeorological data to analyze the hydro-meteorological drought in the Tekeze-Atbara River basin(TAR)in the eastern Sudan utilizing the SPI,SPEI and SRI.Our findings indicated that the dry condition fluctuated over the whole of Sudan at various temporal and spatial scales.The DSI results showed that both the Kordofan and Darfur regions were affected by drought in the period 2001–2005,whereas most regions were affected by drought from 2008 to 2011.The spatial correlation between DSI,SPI-3,and TRMM precipitation products illustrated a significant positive correlation in agricultural lands and negative correlation in mountainous areas.The relationship between DSI and the Standardized variable of crop yield(St.Y)for sorghum yield was also investigated over two main agricultural regions(Central and Eastern regions)for the period 2001–2011,which revealed a good agreement between them,and a huge drop of sorghum yield also occurred in 2008–2011,corresponding to extreme drought indicated by DSI.In general,drought exhibited increasing impacts on sorghum across the growing season from July to October.Little effect was found in July(green-up stage),and significant impacts were seen in August(0.39)and September(0.57).Sorghum yield is likely going to face increased stress in Sudan,as a consequence of variations in climate factors,such as precipitation and temperature.The present study indicated that DSI can be used for agricultural drought monitoring and served as an alternative indicator for the estimation of crop yield over Sudan in some levels.For meteorological drought the results showed that the period between 1975 and 1981 was dominated by wet conditions;second,from 1982 to 1992,a period of drought ranging from moderate dry to extreme dry conditions.The analysis of general modes of hydrological drought in the Atbara River Basin showed that severe drought was observed in 1972,1983-1987,1991 and 2002-2004,normal and moderately wet since 1998-2000.High correlation values 0.78(at 12-month scale)and 0.42(at 3-month scale)show comparativeness in the performance between SPI and SPEI.Stronger correlation value(0.22)was obtained between SRI and SPEI for 6-month time intervals.Lesser value was obtained between SPI and SRI in same time interval(0.21).A weaker positive value(0.18)obtained at 9-month.The analysis of the frequency of the various conditions suggested that 80% of the study duration had observed mostly normal moisture conditions,followed by 7% of duration for both moderately wet and dry conditions and 3% of duration had extreme drought and flood conditions each.The analysis of rainfall and temperature in Atbara River Basin,indicated that the hydrological drought are more affected by precipitation(drying)than temperature(warming)in the basin.The comparison between the SRI for the period 1971-2011 at the Atbara River and El Nino index 3.4 showed that La Nina event was followed by El Nino event.Moreover,the results showed that El Ni?o has a greater impact on the seasonal runoff.We also found that the season with maximum effect of runoff was start in the months of May to July(MJJ)of the El Nino year.Overall,the drought is controlled by the nature of the 7-year cycle suggested droughts will possibly re-occur in the future.The outcomes of this research could be used to motivate future studies in the elaboration of crop models to forecast crops product based on physiological processes during plant development considering water requirement to take enough measures to reduce the impacts of drought spells.Moreover,the results are very important for water management and disaster,both in case of the adverse(e.g.loss of life and agriculture production)and positive(e.g.energy,dispersion of nutrients in agricultural lands)impacts of fluctuations in runoff.Moreover,it should be considered to implement a drought monitor system in the Sudan as a significant tool of early warning system and as an indicator for the efficient water resources management.