An Index-Based Approach to Assess the Water Availability for Irrigated Agriculture in Sub-Saharan Africa

Agriculture is a major economic sector in sub-Saharan African (SSA) countries, where it contributes 32 percent of the gross domestic product (GDP) and employs 65 percent of the population. However, SSA countries are farming only a small percentage of their potential cultivable area and are using only a fraction of their renewable water resources. Moreover, despite the importance of land and water resources in SSA, especially in rural areas, there has been little research on their potential. In this study, an index was developed to assess the potential for agriculture, considering renewable water availability of both surface water and groundwater. The index-based approach was then used to assess the potential increase in arable land area in 15 selected SSA countries. The selected countries were classified using the index, based on the availability of renewable water resources nationwide. We also assessed the future water demand by employing three scenarios and combining different rain-fed and irrigated options. The results show that, except for Zimbabwe, the current available surface water or groundwater resources could be sufficient to farm all of the potential cultivable areas in the selected countries when both rain-fed and irrigated systems are fully operational. The findings also indicate that targeted infrastructure projects (e.g., reservoirs, channels), crop management, and water saving techniques could improve surface and groundwater availability in the SSA region

The role of agriculture expansion in water resources depletion in central Iran

Abstract In arid and semi-arid regions, water is considered as the main resource for agriculture and therefore for the mainstay of rural societies. In this study, agricultural water usage sustainability in Fars Province, Zayanderud and Bakhtegan Basins, in central Iran was evaluated. The study areas have witnessed a depletion in main river flows and groundwater levels, directly affecting the water security and the well-being on the local inhabitants. Available and developed drought indicators such as: Standardized Precipitation Index (SPI), Stream Drought Index (SDI), Overall Agricultural Drought Index (OADI) and Agricultural Drought Index (ADI) were used. This indicators in addition to remote sensed and in-situ data were used to monitor the water depletion in these areas. Results indicated that both Fars and Zayanderud went through three sustainability water usage stages during a period of 40 year: 1) a sustainable phase, where the water usage matched the water renewability capacity; 2) a transition phase, where water usage occasionally exceeds the water renewability capacity; 3) an unsustainable phase, where there is a lack and depletion in water resources for agriculture and domestic usage. Climatically there was no significant distribution of meteorological drought, and no negative trends in the annual precipitation, in Fars and Zayanderud. A hyper-arid climate prevailed for an average of 32 percent of the Fars province spatio-temporal coverage during the study period. The area increased significantly from 30.6 percent in the first decade, 1977 till 1986 to 44.4 percent in the last decade, 2007–2016. In Zayanderud the hyper-arid cold climate was dominant in the study period, with an average 57.5 percent frequency of occurrence. Most of the years, 86 percent of the period from 1977 till 2016, are considered to be wet and normal years meteorologically, and the climatic diversity remained constant with no significant negative trend in Fars. In contrary, the hydrological drought occurrence increased significantly from 30 to 73 percent of the years, especially after the 1980s when the irrigation expanded and 60 percent of the rainfed areas were converted to irrigated areas. This exerted a substantial pressure on surface and groundwater resources for irrigation purposes, led to groundwater depletion in major aquifers in Fars and Zayanderud, reaching 50 meters in some aquifers, and zero flow in the downstream of main rivers. This decrease in the downstream flow of the Zayanderud and Kor Rivers led to the decrease in the surface volume of Gavkhuni Wetland and Bakhtegan Lake. The wetland and the lake reached to complete dryness in several occasion, exerting pressure on the environment and surrounding ecology. The increase in water pressure and the depletion of its resources led to the decrease in the irrigated areas to half, after the farms doubled the irrigated areas in the 1990s. The remote sensed data confirmed this results were the Gravity Recovery and Climate Experiment (GRACE) and the Global Land Data Assimilation System (GLDAS) derived data showed the total water mass depletion in the Zayanderud and Bakhtegan Basins, and the groundwater levels depletion in Bakhtegan. GRACE data showed an average water mass monthly depletion of 32 millimeters (mm) in Zayanderud and 17.5 mm in Bakhtegan. The Normalized Water Difference Index (NDWI), confirmed the surface area depletion in the Gavkhuni Wetland reaching total dryness in the year 2009 onwards. As a main conclusion, the increase in the hydrological and agricultural droughts occurrence in Fars and Zayanderud seem to be directly related to human farming activities, even with the occurrence of meteorological droughts.Tiivistelmä Kuivilla seuduilla vesi on maanviljelyn tärkein resurssi ja siten myös maalaisyhteisöjen tukipilari. Tässä tutkimuksessa arvioitiin Iranin keski- ja eteläosissa sijaitsevien Farsin provinssin sekä Zayanderudin ja Bakhteganin valuma-alueiden maatalouden veden käytön kestävyyttä. Tutkimusalueiden suurimpien jokien virtaamat ja pohjaveden tasot ovat ehtyneet, mikä vaikuttaa suoraan vedensaantiin ja paikallisten asukkaiden hyvinvointiin. Näillä alueilla veden ehtymistä seurattiin olemassa olevilla ja kehitetyillä kuivuusindekseillä keräämällä dataa sekä kaukokartoituksella että paikan päällä. Tuloksi havaittiin, että tutkimusalueilla ollaan käyty läpi kolme veden kulutuksen vaihetta neljänkymmenen vuoden aikana: 1) Kulutusta kestävä vaihe, jolloin veden käyttö oli suhteessa veden uusiutumiskapasiteettiin; 2) Siirtymävaihe, jolloin veden käyttö toisinaan ylittää veden uusiutumiskapasiteettiin; 3) Kestämätön vaihe, jolloin on vesivaroissa on puutetta ja maatalouden ja kotitalouksien käyttöön varojen ehtyessä. Ilmastollisesti tutkimusalueilla ei ollut merkittäviä säännöllisiä kuivuuskausia, eikä negatiivisia trendejä vuosittaisessa sademäärissä. Suurin osa tarkastelluista vuosista 1977–2016 oli joko kosteita tai normaaleita ilmastotieteellisessä mielessä. Ilmaston monimuotoisuus pysyi Farsissa tutkimusaikana muuttumattomana, eikä siinä havaittu merkittäviä negatiivisia trendejä. Hydrologinen kuivuus kuitenkin lisääntyi merkittävästi eritoten 1980-luvun jälkeen, kun keinokastelu lisääntyi ja 60 prosenttia sadekastelun varassa olleista alueista muunnettiin keinokastelluiksi. Tämä aiheutti merkittävää painetta pinta- ja pohjavesivaroihin, mikä johti pohjavesien ehtymiseen suurissa pohjavesivarannoissa Farsissa ja Zayanderudissa, sekä suurimpien jokien alavirtojen tyrehtymiseen. Tutkimusalueen Zayanderud- ja Kor-jokien alavirtojen valunnan väheneminen johti Gavkhunin suon ja Bakhtegan-järven pinta-alojen pienenemiseen. Suo ja järvi kuivuivat useaan otteeseen kokonaan, tuottaen suurta painetta ympäristölle ja ympäröivälle ekologialle. Veden käyttöpaineen kohoaminen ja alueen resurssien ehtyminen johtivat kasteltujen alueiden vähenemiseen maatilojen lisättyä kasteltuja alueita 1990-luvulla. Kaukokartoituksella kerätty data vahvistaa nämä löydöt. Painovoimaan perustuvalla GRACE-satelliitilla kerätty data osoitti Zayanderudin ja Bakhteganin valuma-alueiden kokonaisvesimassan ehtymisen ja pohjaveden ehtymisen Bakhteganissa. Vesi-indeksitarkastelu (NDWI) vahvisti sekä Gavkhunin suon, että Bakhtegan-järven pinta-alojen pienenemisen. Johtopäätelmänä tutkimuksesta oli, että vaikka alueella on ajoittaisia kuivuuskausia, hydrologisen ja maataloudellisen kuivuuden esiintymisen lisääntyminen Farsissa ja Zayanderudisda näyttää olevan suorassa yhteydessä ihmisten maanviljelytoimintaan

Expanding the Irrigated Areas in the MENA and Central Asia: Challenges or Opportunities?

Middle Eastern, North African countries (MENA), and Central Asian countries are considered the countries most facing water and food scarcity. The current water exploitation indicates that a few countries are overexploiting their water resources and using the fossil water available. This study reviews each country’s renewable water resources volume and evaluates the resources available to expand the agricultural area. Different scenarios are considered, using both irrigated and rainfed farming options, for concluding the most sustainable farming method in each country. Different scenarios are considered using irrigated and rainfed farming options to recommend the most sustainable farming method for each country. Results show that the countries in the MENA and Central Asia can be divided into three main categories: (1) Countries whose expansion of agricultural area can only be applied by using fossil water resources (Bahrain, Egypt, Kuwait, Libya, Qatar, Saudi Arabia, Turkmenistan, United Arab Emirates, and Uzbekistan); (2) Countries where the agricultural area can be expanded to a certain limit, by sustainably using both irrigated and rainfed farming (Afghanistan, Algeria, Iran, Palestine, Jordan, Kazakhstan, Morocco, Oman, Syria, Tajikistan, Tunisia, and Yemen); (3) Countries that have enough renewable water resources to farm all their agricultural area (Lebanon, Iraq, Turkey, and Kyrgyzstan). However, the aim of this study and its results are only to assess the renewable water resources available to sustain the increased agricultural water demand by setting aside other agricultural factors that constrain the sector

Expanding the irrigated areas in the MENA and Central Asia:challenges or opportunities?

Abstract Middle Eastern, North African countries (MENA), and Central Asian countries are considered the countries most facing water and food scarcity. The current water exploitation indicates that a few countries are overexploiting their water resources and using the fossil water available. This study reviews each country’s renewable water resources volume and evaluates the resources available to expand the agricultural area. Different scenarios are considered, using both irrigated and rainfed farming options, for concluding the most sustainable farming method in each country. Different scenarios are considered using irrigated and rainfed farming options to recommend the most sustainable farming method for each country. Results show that the countries in the MENA and Central Asia can be divided into three main categories: (1) Countries whose expansion of agricultural area can only be applied by using fossil water resources (Bahrain, Egypt, Kuwait, Libya, Qatar, Saudi Arabia, Turkmenistan, United Arab Emirates, and Uzbekistan); (2) Countries where the agricultural area can be expanded to a certain limit, by sustainably using both irrigated and rainfed farming (Afghanistan, Algeria, Iran, Palestine, Jordan, Kazakhstan, Morocco, Oman, Syria, Tajikistan, Tunisia, and Yemen); (3) Countries that have enough renewable water resources to farm all their agricultural area (Lebanon, Iraq, Turkey, and Kyrgyzstan). However, the aim of this study and its results are only to assess the renewable water resources available to sustain the increased agricultural water demand by setting aside other agricultural factors that constrain the sector

An Index-Based Approach to Assess the Water Availability for Irrigated Agriculture in Sub-Saharan Africa

Agriculture is a major economic sector in sub-Saharan African (SSA) countries, where it contributes 32 percent of the gross domestic product (GDP) and employs 65 percent of the population. However, SSA countries are farming only a small percentage of their potential cultivable area and are using only a fraction of their renewable water resources. Moreover, despite the importance of land and water resources in SSA, especially in rural areas, there has been little research on their potential. In this study, an index was developed to assess the potential for agriculture, considering renewable water availability of both surface water and groundwater. The index-based approach was then used to assess the potential increase in arable land area in 15 selected SSA countries. The selected countries were classified using the index, based on the availability of renewable water resources nationwide. We also assessed the future water demand by employing three scenarios and combining different rain-fed and irrigated options. The results show that, except for Zimbabwe, the current available surface water or groundwater resources could be sufficient to farm all of the potential cultivable areas in the selected countries when both rain-fed and irrigated systems are fully operational. The findings also indicate that targeted infrastructure projects (e.g., reservoirs, channels), crop management, and water saving techniques could improve surface and groundwater availability in the SSA regio

Monitoring Groundwater Storage Depletion Using Gravity Recovery and Climate Experiment (GRACE) Data in Bakhtegan Catchment, Iran

The Bakhtegan catchment, an important agricultural region in south-western Iran, has suffered groundwater depletion in recent years. As groundwater is considered the main source of fresh water in the catchment, especially for agriculture, monitoring groundwater responses to irrigation is important. Gravity Recovery and Climate Experiment (GRACE) satellite data can help determine water mass changes in catchments and assess water volume changes. In this study, we compared GRACE-derived water mass data against groundwater volume variations measured in situ. We also assessed the efficiency of GRACE-derived data in catchments smaller than the 200,000 km2 recommended area when using GRACE. For the study period (January 2002 through December 2011), the GRACE data showed a 7.6 mm annual decline in groundwater level, with a total volume loss of 2.6 km3 during the period. The in situ monthly measurements of groundwater level showed an average depletion of 10 m in catchment aquifers during the study period. This depletion rate was supported by the recorded decrease in precipitation volume, especially in the post-drought period after 2007. These results demonstrate that GRACE can be useful tool for monitoring groundwater depletion in arid catchments

Evaluating Impacts of Irrigation and Drought on River, Groundwater and a Terminal Wetland in the Zayanderud Basin, Iran

The Zayanderud Basin is an important agricultural area in central Iran. In the Basin, irrigation consumes more than 90 percent of the water used, which threatens both the downstream historical city of Isfahan and the Gavkhuni Wetland reserve—the final recipient of the river water. To analyze impacts of land use changes and the occurrence of metrological and hydrological drought, we used groundwater data from 30 wells, the standardized precipitation index (SPI) and the streamflow drought index (SDI). Changes in the wetland were analyzed using normalized difference water index (NDWI) values and water mass depletion in the Basin was also assessed with gravity recovery and climate experiment (GRACE)-derived data. The results show that in 45 out of studied 50 years, the climate can be considered as normal in respect to mean precipitation amount, but hydrological droughts exist in more than half of the recorded years. The hydrological drought occurrence increased after the 1970s when large irrigation schemes were introduced. In recent decades, the flow rate reached zero in the downstream part of the Zayanderud River. NDWI values confirmed the severe drying of the Gavkhuni Wetland on several occasions, when compared to in situ data. The water mass depletion rate in the Basin is estimated to be 30 (±5) mm annually; groundwater exploitation has reached an average of 365 Mm3 annually, with a constant annual drop of 1 to 2.5 meters in the groundwater level annually. The results demonstrate the connection between groundwater and surface water resources management and highlight that groundwater depletion and the repeated occurrence of the Zayanderud River hydrological drought are directly related to human activities. The results can be used to assess sustainability of water management in the Basin

An index-based approach to assess the water availability for irrigated agriculture in Sub-Saharan Africa

Abstract Agriculture is a major economic sector in sub-Saharan African (SSA) countries, where it contributes 32 percent of the gross domestic product (GDP) and employs 65 percent of the population. However, SSA countries are farming only a small percentage of their potential cultivable area and are using only a fraction of their renewable water resources. Moreover, despite the importance of land and water resources in SSA, especially in rural areas, there has been little research on their potential. In this study, an index was developed to assess the potential for agriculture, considering renewable water availability of both surface water and groundwater. The index-based approach was then used to assess the potential increase in arable land area in 15 selected SSA countries. The selected countries were classified using the index, based on the availability of renewable water resources nationwide. We also assessed the future water demand by employing three scenarios and combining different rain-fed and irrigated options. The results show that, except for Zimbabwe, the current available surface water or groundwater resources could be sufficient to farm all of the potential cultivable areas in the selected countries when both rain-fed and irrigated systems are fully operational. The findings also indicate that targeted infrastructure projects (e.g., reservoirs, channels), crop management, and water saving techniques could improve surface and groundwater availability in the SSA region

Monitoring groundwater storage depletion using gravity recovery and climate experiment (GRACE) data in Bakhtegan catchment, Iran

Abstract The Bakhtegan catchment, an important agricultural region in south-western Iran, has suffered groundwater depletion in recent years. As groundwater is considered the main source of fresh water in the catchment, especially for agriculture, monitoring groundwater responses to irrigation is important. Gravity Recovery and Climate Experiment (GRACE) satellite data can help determine water mass changes in catchments and assess water volume changes. In this study, we compared GRACE-derived water mass data against groundwater volume variations measured in situ. We also assessed the efficiency of GRACE-derived data in catchments smaller than the 200,000 km2 recommended area when using GRACE. For the study period (January 2002 through December 2011), the GRACE data showed a 7.6 mm annual decline in groundwater level, with a total volume loss of 2.6 km3 during the period. The in situ monthly measurements of groundwater level showed an average depletion of 10 m in catchment aquifers during the study period. This depletion rate was supported by the recorded decrease in precipitation volume, especially in the post-drought period after 2007. These results demonstrate that GRACE can be useful tool for monitoring groundwater depletion in arid catchments

The impact of Turkey’s water resources development on the flow regime of the Tigris River in Iraq

Study region: Once, the Tigris River (with its twin, the Euphrates) was the remarkable river in the west of Asia, making Mesopotamia a cradle of civilization thousands of years ago. Upstream anthropogenic activity has choked the Tigris River, the connecting lifeline across Iraq, and, due to droughts and desertification, caused the country to be plagued by poverty. Study focus: Here, we give a perspective on flow regime alteration in the main corridor of the Tigris River at five crucial points (Cizre, Mosul, Baiji, Baghdad, and Kut) before and after the planned water resources development in Turkey. Turkey’s Tigris River regulation goal is to generate about 7247 GWh of energy and irrigate over 640,000 ha of farmlands. New hydrological insights for the region: We reconstructed the natural flow along the Tigris River. In addition, to evaluate hydrological droughts, we proposed a modified streamflow drought index (MSDI) and compared it with the original streamflow drought index (SDI). The results show that the worst hydrological conditions could be found below the Samarra barrage in Iraq before the Tigris River regulation in Turkey. This negative hydrological condition will be extended to the whole corridor of the Tigris River in Iraq after the implementation of Turkey's goal. As a result, for example, Cizre and Mosul will experience extreme conditions in 37.5–87.5% of the years; this means a considerable reduction in the Mosul reservoire’s inflow (135–326 m3/sec). Consequently, some parts of Mosul's hydropower and reservoir capacity will be useless, and hydrological drought upstream of the Samarra barrage will be dominated