Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat ... more Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat systems. Saving water can be elusive in that reducing seepage, percolation and runoff losses from fi elds does not necessarily save water if it can be recaptured at some other temporal or spatial scale, for example by groundwater pumping. Many technologies appear to save substantial amounts of water through reducing irrigation water requirement, but whether these are true water savings is uncertain as components of the water balance have not been quantifi ed. Such technologies include laser levelling, direct drilling, raised beds, non-ponded rice culture and irrigation scheduling. It is questionable whether puddling saves water. Reducing non-benefi cial evaporation losses is a true water saving, and optimal planting time of rice to avoid the period of highest evaporative demand and changing to non-ponded rice culture can save signifi cant amounts of water. However, moving away from puddled, ponded to more aerobic rice culture sometimes brings new production problems. Furthermore, farmers faced with unreliable water supplies need to store water on their fi elds as insurance, and puddling assists retention of water during the rice crop. Rehabilitation and improvement of canal and power systems in Asia, funded by charging according to use, are required to facilitate adoption of many water saving technologies. Australian farmers pay fi xed plus volumetric charges for water to cover the cost of infrastructure and operation of irrigation systems, which are continuously being improved to provide water on demand and minimise losses. They are able to plan their plantings based on knowledge of the likely amount of irrigation water available each season and crop water use requirement, and thus avoid wasting water and fi nancial loss by overplanting and crop failure. Such approaches have the potential to increase production and water productivity in Asia, however the challenge would be to apply them in an equitable way that benefi ts many millions of subsistence farmers.
Global climate change has received much attention worldwide in the scientific as well as in the p... more Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may threaten increasingly many regions. Drought is a natural phenomenon that may cause social, economical and environmental damages to the society. In this 5 20 and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm 3 yr −1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal 25 that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m) and high base flow reduction (> 20 %). This case 2720 HESSD
Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soi... more Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative -using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590-42,620 km 2 . The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600-1,600 km 2 . The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km 2 ). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.
Journal of the American Water Resources Association, 2011
Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soi... more Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative -using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590-42,620 km 2 . The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600-1,600 km 2 . The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km 2 ). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.
Physics and Chemistry of the Earth, Parts A/B/C, 2009
... Ilyas Masih a , b , Corresponding Author Contact Information , E-mail The Corresponding Autho... more ... Ilyas Masih a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Mobin-ud-Din Ahmad a , 1 , Stefan Uhlenbrook b ... The Karkheh basin remained unregulated by the large dams before the completion of the Karkheh dam in 2001 (details on dams ...
IWMI's mission is to improve water and land resources management for food, livelihoods and nature... more IWMI's mission is to improve water and land resources management for food, livelihoods and nature. In serving this mission, IWMI concentrates on the integration of policies, technologies and management systems to achieve workable solutions to real problems-practical, relevant results in the field of irrigation and water and land resources.
... JAMAB Consulting Engineers in association with Ministry of Energy, Iran. Masih, I., S. Uhlenb... more ... JAMAB Consulting Engineers in association with Ministry of Energy, Iran. Masih, I., S. Uhlenbrook, MD Ahmad, and S. Maskey, 2008. ... 2007. Land use change detection in KRB by using multi-temporal satellite images. In Ghafouri, M.(ed.) Extended abstracts. ...
Water-limited environments occupy about half of the global land area and are highly sensitive to ... more Water-limited environments occupy about half of the global land area and are highly sensitive to change due to scarcity and variable distribution of water and nutrients. The Karkheh basin in Iran is in a water limited region which exhibits increasing competition for scarce water resources between irrigation, domestic, hydropower and environmental needs. Increasing demands for water are making sustainable water management more and more difficult particularly because of lack of understanding of basin hydrology and impacts of water resource development on different users across the basin. An in-depth study was conducted to examine the inter-annual and long-term variability of surface water resource using daily stream flow data from 1961 to 2001 at seven key locations across the Karkheh basin. The water accounting at basin scale was carried out using the available information for the water year 1993-94, which is considered in Iran as the reference year for future development and allocation of water resources in the Karkheh basin. The analysis reveals that water allocation planning on the basis of mean annual surface water availability can only provide a supply security of about 45 %, ranging from 40 to 52 percent. Although, the water allocations to different sectors are lower than the available resources and the competition among different sectors of water use is minimal during the study period, it would be extremely difficult to meet the demands in future i.e. by 2025, as planned allocation will reach close to the annual renewable water resources available in an average climatic year. The competition among irrigation and other sectors will keep increasing in future, particularly during dry years. The analysis conducted in this study is helpful in gaining further insights into the hydrological variability of surface water resources and incorporating it into water development and allocation strategies that will contribute in ensuring the sustained productivity from irrigated agriculture and other uses of water in the coming decades.
ABSTRACT Increasing the productivity of rice-wheat cropping systems is critical for meeting food ... more ABSTRACT Increasing the productivity of rice-wheat cropping systems is critical for meeting food demand in rapidly growing South Asia. But this must be done with increasingly scarce water resources, bringing greater attention to Resource Conservation Technologies (RCTs) such as zero tillage, laser land leveling and furrow bed planting. While the impacts of RCTs on yields are easy to measure and explain, impacts on water savings are not well understood beyond the field scale because of the complex movement of water. This paper uses both physical measurements and farmer survey data from the rice-wheat cropping system of Punjab, Pakistan to explain the main drivers of RCT adoption and their impacts on land and water productivity and water savings across scales. The primary drivers for RCT adoption (zero tillage wheat and laser land leveling) were reduced costs of production and labor requirements, reduced field scale irrigation water application, and higher yield. While the large proportion of farmers benefitting from RCTs explains overall increases in RCT adoption, a considerable proportion (30% of zero tillage adopters for wheat cultivation) reported yield loss, highlighting the need for further technological refinement and enhancing farmers' ability to implement RCT. The study also indicates that the field scale reduction in irrigation application did not always translate into real water savings or reductions in water use at farm, cropping system and catchment scales, especially in areas where deep percolation from the root zone could be reused as groundwater irrigation. Finally, the evidence shows that medium and large farmers tended to use the field scale irrigation savings to increase their cropped area. This finding suggests that without regulations and policies to regulate the use of "saved" water, adoption of RCTs can result in overall increased water use with implications for the long-term sustainability of irrigated agriculture.
The downstream impacts of increasing water consumption in the upstream rain-fed areas of the Kark... more The downstream impacts of increasing water consumption in the upstream rain-fed areas of the Karkheh Basin, Iran are simulated using the semi-distributed SWAT model. Three scenarios are tested at subbasin and basin levels: converting rain-fed areas to irrigation agriculture (S1), improving soil water availability through rainwater harvesting (S2), and a combination of both (S3). The results of these scenarios were compared against the baseline period 1988-2000. The S1 scenario shows a 10% reduction in mean annual flow at the basin level, varying from 8-15% across the subbasins. The reductions in mean monthly flows are in the range of 1-56% at the basin level, with June witnessing the highest flow reduction. Flow reductions are comparatively higher in the upstream parts of the basin, as a result of a relatively higher potential of developing rain-fed areas coupled with comparatively lower amount of available runoff. The impacts of S2 are generally small with reductions of 2-5% and 1-9% in mean annual and mean monthly flows, respectively. The results of S3 are in general similar to those of S1. Although the estimated annual flow reductions remain well within the available water resources development potential, measures needs to be taken to avoid excessive flow reductions in May, June and July. It is recommended that only a limited agricultural area should be converted from rain-fed to irrigated agriculture (about 0.1 million ha), and should practice supplementary irrigation. The supplies should also be augmented through developing additional water storage. Adopting such measures is extremely important for the upper subbasins Gamasiab and Qarasou where comparatively higher flow reductions were estimated.
Hydrology and Earth System Sciences Discussions, 2014
This paper presents a comprehensive review and analysis of the available literature and informati... more This paper presents a comprehensive review and analysis of the available literature and information on droughts to build a continental, regional and country level perspective on geospatial and temporal variation of droughts in Africa. The study is based on the review and analysis of droughts occurred during 1900-2013, as well as evidence available from past centuries based on studies on the lake sediment analysis, tree-ring chronologies and written and oral histories and future predictions from the global climate change models. Most of the studies based on instrumental records indicate that droughts have become more frequent, intense and widespread during the last 50 years. The extreme droughts of
Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat ... more Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat systems. Saving water can be elusive in that reducing seepage, percolation and runoff losses from fi elds does not necessarily save water if it can be recaptured at some other temporal or spatial scale, for example by groundwater pumping. Many technologies appear to save substantial amounts of water through reducing irrigation water requirement, but whether these are true water savings is uncertain as components of the water balance have not been quantifi ed. Such technologies include laser levelling, direct drilling, raised beds, non-ponded rice culture and irrigation scheduling. It is questionable whether puddling saves water. Reducing non-benefi cial evaporation losses is a true water saving, and optimal planting time of rice to avoid the period of highest evaporative demand and changing to non-ponded rice culture can save signifi cant amounts of water. However, moving away from puddled, ponded to more aerobic rice culture sometimes brings new production problems. Furthermore, farmers faced with unreliable water supplies need to store water on their fi elds as insurance, and puddling assists retention of water during the rice crop. Rehabilitation and improvement of canal and power systems in Asia, funded by charging according to use, are required to facilitate adoption of many water saving technologies. Australian farmers pay fi xed plus volumetric charges for water to cover the cost of infrastructure and operation of irrigation systems, which are continuously being improved to provide water on demand and minimise losses. They are able to plan their plantings based on knowledge of the likely amount of irrigation water available each season and crop water use requirement, and thus avoid wasting water and fi nancial loss by overplanting and crop failure. Such approaches have the potential to increase production and water productivity in Asia, however the challenge would be to apply them in an equitable way that benefi ts many millions of subsistence farmers.
Global climate change has received much attention worldwide in the scientific as well as in the p... more Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may threaten increasingly many regions. Drought is a natural phenomenon that may cause social, economical and environmental damages to the society. In this 5 20 and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm 3 yr −1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal 25 that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m) and high base flow reduction (> 20 %). This case 2720 HESSD
Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soi... more Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative -using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590-42,620 km 2 . The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600-1,600 km 2 . The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km 2 ). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.
Journal of the American Water Resources Association, 2011
Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soi... more Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative -using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590-42,620 km 2 . The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600-1,600 km 2 . The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km 2 ). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.
Physics and Chemistry of the Earth, Parts A/B/C, 2009
... Ilyas Masih a , b , Corresponding Author Contact Information , E-mail The Corresponding Autho... more ... Ilyas Masih a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Mobin-ud-Din Ahmad a , 1 , Stefan Uhlenbrook b ... The Karkheh basin remained unregulated by the large dams before the completion of the Karkheh dam in 2001 (details on dams ...
IWMI's mission is to improve water and land resources management for food, livelihoods and nature... more IWMI's mission is to improve water and land resources management for food, livelihoods and nature. In serving this mission, IWMI concentrates on the integration of policies, technologies and management systems to achieve workable solutions to real problems-practical, relevant results in the field of irrigation and water and land resources.
... JAMAB Consulting Engineers in association with Ministry of Energy, Iran. Masih, I., S. Uhlenb... more ... JAMAB Consulting Engineers in association with Ministry of Energy, Iran. Masih, I., S. Uhlenbrook, MD Ahmad, and S. Maskey, 2008. ... 2007. Land use change detection in KRB by using multi-temporal satellite images. In Ghafouri, M.(ed.) Extended abstracts. ...
Water-limited environments occupy about half of the global land area and are highly sensitive to ... more Water-limited environments occupy about half of the global land area and are highly sensitive to change due to scarcity and variable distribution of water and nutrients. The Karkheh basin in Iran is in a water limited region which exhibits increasing competition for scarce water resources between irrigation, domestic, hydropower and environmental needs. Increasing demands for water are making sustainable water management more and more difficult particularly because of lack of understanding of basin hydrology and impacts of water resource development on different users across the basin. An in-depth study was conducted to examine the inter-annual and long-term variability of surface water resource using daily stream flow data from 1961 to 2001 at seven key locations across the Karkheh basin. The water accounting at basin scale was carried out using the available information for the water year 1993-94, which is considered in Iran as the reference year for future development and allocation of water resources in the Karkheh basin. The analysis reveals that water allocation planning on the basis of mean annual surface water availability can only provide a supply security of about 45 %, ranging from 40 to 52 percent. Although, the water allocations to different sectors are lower than the available resources and the competition among different sectors of water use is minimal during the study period, it would be extremely difficult to meet the demands in future i.e. by 2025, as planned allocation will reach close to the annual renewable water resources available in an average climatic year. The competition among irrigation and other sectors will keep increasing in future, particularly during dry years. The analysis conducted in this study is helpful in gaining further insights into the hydrological variability of surface water resources and incorporating it into water development and allocation strategies that will contribute in ensuring the sustained productivity from irrigated agriculture and other uses of water in the coming decades.
ABSTRACT Increasing the productivity of rice-wheat cropping systems is critical for meeting food ... more ABSTRACT Increasing the productivity of rice-wheat cropping systems is critical for meeting food demand in rapidly growing South Asia. But this must be done with increasingly scarce water resources, bringing greater attention to Resource Conservation Technologies (RCTs) such as zero tillage, laser land leveling and furrow bed planting. While the impacts of RCTs on yields are easy to measure and explain, impacts on water savings are not well understood beyond the field scale because of the complex movement of water. This paper uses both physical measurements and farmer survey data from the rice-wheat cropping system of Punjab, Pakistan to explain the main drivers of RCT adoption and their impacts on land and water productivity and water savings across scales. The primary drivers for RCT adoption (zero tillage wheat and laser land leveling) were reduced costs of production and labor requirements, reduced field scale irrigation water application, and higher yield. While the large proportion of farmers benefitting from RCTs explains overall increases in RCT adoption, a considerable proportion (30% of zero tillage adopters for wheat cultivation) reported yield loss, highlighting the need for further technological refinement and enhancing farmers' ability to implement RCT. The study also indicates that the field scale reduction in irrigation application did not always translate into real water savings or reductions in water use at farm, cropping system and catchment scales, especially in areas where deep percolation from the root zone could be reused as groundwater irrigation. Finally, the evidence shows that medium and large farmers tended to use the field scale irrigation savings to increase their cropped area. This finding suggests that without regulations and policies to regulate the use of "saved" water, adoption of RCTs can result in overall increased water use with implications for the long-term sustainability of irrigated agriculture.
The downstream impacts of increasing water consumption in the upstream rain-fed areas of the Kark... more The downstream impacts of increasing water consumption in the upstream rain-fed areas of the Karkheh Basin, Iran are simulated using the semi-distributed SWAT model. Three scenarios are tested at subbasin and basin levels: converting rain-fed areas to irrigation agriculture (S1), improving soil water availability through rainwater harvesting (S2), and a combination of both (S3). The results of these scenarios were compared against the baseline period 1988-2000. The S1 scenario shows a 10% reduction in mean annual flow at the basin level, varying from 8-15% across the subbasins. The reductions in mean monthly flows are in the range of 1-56% at the basin level, with June witnessing the highest flow reduction. Flow reductions are comparatively higher in the upstream parts of the basin, as a result of a relatively higher potential of developing rain-fed areas coupled with comparatively lower amount of available runoff. The impacts of S2 are generally small with reductions of 2-5% and 1-9% in mean annual and mean monthly flows, respectively. The results of S3 are in general similar to those of S1. Although the estimated annual flow reductions remain well within the available water resources development potential, measures needs to be taken to avoid excessive flow reductions in May, June and July. It is recommended that only a limited agricultural area should be converted from rain-fed to irrigated agriculture (about 0.1 million ha), and should practice supplementary irrigation. The supplies should also be augmented through developing additional water storage. Adopting such measures is extremely important for the upper subbasins Gamasiab and Qarasou where comparatively higher flow reductions were estimated.
Hydrology and Earth System Sciences Discussions, 2014
This paper presents a comprehensive review and analysis of the available literature and informati... more This paper presents a comprehensive review and analysis of the available literature and information on droughts to build a continental, regional and country level perspective on geospatial and temporal variation of droughts in Africa. The study is based on the review and analysis of droughts occurred during 1900-2013, as well as evidence available from past centuries based on studies on the lake sediment analysis, tree-ring chronologies and written and oral histories and future predictions from the global climate change models. Most of the studies based on instrumental records indicate that droughts have become more frequent, intense and widespread during the last 50 years. The extreme droughts of
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