. The impact of drought on environmental flow (EF) in 27 catchments of the Indus basin is studied... more . The impact of drought on environmental flow (EF) in 27 catchments of the Indus basin is studied from 1980–2018 using the Indicators of Hydrologic Alterations (IHA). The standardized Precipitation Evapotranspiration Index (SPEI) was systematically propagated from one catchment to another using principal component analysis (PCA). Threshold regression is used to determine the severity of drought (scenario-1) and month (scenario-2) that trigger low flows in the Indus Basin. The impact of drought on low EFs is quantified using the Range of variability analysis (RVA). The hydrological alteration factor (HAF) is calculated for each catchment in the Indus basin. The results show that most of the catchments are vulnerable to drought during the periods 1984–1986, 1991/1992, 1997 to 2003, 2007 to 2008, 2012 to 2013, and 2017 to 2018. On a higher time scale (SPEI-12), drought is more severe in Lower Indus Basin (LIB) than in the Upper Indus Basin (UIB). IHA pointed out that drought significantly impacts the distribution of environmental flow components, particularly extreme low flow (ELF) and low flow (LF). The magnitude and frequency of the ELF and LF events increase as drought severity increases. The threshold regression provided useful insights indicating that moderate drought can trigger ELF and LF at shorter time scales (SPEI-1 and SPEI-6) in the UIB and Middle Indus Basin (MIB). Conversely, severe and extreme drought triggers ELF and LF at higher time scales (SPEI-12) in LIB. The threshold regression also divided the entire study period (1980–2018) into different time zones (scenario-2), which is useful in quantifying the impact of drought on low EFs using the SPEI coefficient. Higher SPEI coefficients are observed in LIB, indicating high alterations in EF due to drought. HAF showed high alterations in EF in most of the catchments throughout the year except in August and September. The alterations are subject to several factors, including climate change, seasonality of the river flow, land use changes, topography, and anthropogenic activities. Overall, this study provided useful insights for analyzing the effects of drought on EF, especially during low flows.
This study aims to comprehend the propagation of meteorological drought (expressed by Standardize... more This study aims to comprehend the propagation of meteorological drought (expressed by Standardized Precipitation Evapotranspiration Index, SPEI) into hydrological drought (expressed by Standardized Runoff Index, SRI) using the combined application of Principal Component Analysis (PCA) and Wavelet analysis for a period of 39-year (1980-2018) in the Indus Basin, Pakistan. PCA was used to calculate principal components of precipitation, temperature, and streamflow, which were used to systematically assess the drought propagation from one catchment to another, resulting in a catchment scale drought assessment. The systematic propagation of drought was useful in capturing the effects of local climate variability in the 27 catchments of the Indus Basin. Wavelet analyses are used to calculate the variability of SPEI/SRI and propagation (analyzed with the wavelet coherence) from SPEI to SRI. The propagation time from SPEI to SRI was cross-correlated. SPEI/SRI time-series showed extreme/seve...
Due to its scarcity, wastewater reuse has become an essential element in water resources and agri... more Due to its scarcity, wastewater reuse has become an essential element in water resources and agriculture planning and management in arid regions. This research aimed to study the effect of irrigation with diluted wastewater on the yield, water use efficiency (WUE), fecal coliform bacteria count, and toxic metals in relation to the root and the fruit of okra and eggplant crops under surface and subsurface drip irrigation systems. A strip plot design (split block) was used in field crop experiments carried out over two consecutive seasons (2011 and 2012) at an agriculture research station in the Western region of Saudi Arabia. The main plot treatments contained six wastewater qualities and two irrigation systems arranged in strips with subplots of 2 × 3 m each. The results showed no significant difference between the two irrigation systems on the fruit yield/ha and WUE of okra, while in eggplant, the subsurface irrigation showed a significant difference. On the other hand, the root to...
Due to aridity, scarcity and unsustainably of natural water resources many developing countries t... more Due to aridity, scarcity and unsustainably of natural water resources many developing countries tend to utilize wastewater for crop production. The use of treated wastewater in irrigation has many advantages and disadvantages to soil, crop and environment. The objective of the study was to investigate the effect of irrigation with wastewater on soil physical and hydraulic properties of soil, as well as the effect on yield, yield components and irrigation water use efficiency (IWUE) of vegetable crop grown under surface and subsurface drip irrigation systems. Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural field site in Saudi Arabia. A strip plot design (split block) was constructed to maintain six wastewater qualities. Crop water requirement was calculated by Penman Monteith equation for dry land condition. Physical and hydraulic properties of soil were analyzed at pre-season and post-season to quantify the impact of wastewater trea...
Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultura... more Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant's effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing se...
Due to its scarcity, wastewater reuse has become an essential element in water resources and agri... more Due to its scarcity, wastewater reuse has become an essential element in water resources and agriculture planning and management in arid regions. This research aimed to study the effect of irrigation with diluted wastewater on the yield, water use efficiency (WUE), fecal coliform bacteria count, and toxic metals in relation to the root and the fruit of okra and eggplant crops under surface and subsurface drip irrigation systems. A strip plot design (split block) was used in field crop experiments carried out over two consecutive seasons (2011 and 2012) at an agriculture research station in the Western region of Saudi Arabia. The main plot treatments contained six wastewater qualities and two irrigation systems arranged in strips with subplots of 2 × 3 m each. The results showed no significant difference between the two irrigation systems on the fruit yield/ha and WUE of okra, while in eggplant, the subsurface irrigation showed a significant difference. On the other hand, the root to...
Due to aridity, scarcity and unsustainably of natural water resources many developing countries t... more Due to aridity, scarcity and unsustainably of natural water resources many developing countries tend to utilize wastewater for crop production. The use of treated wastewater in irrigation has many advantages and disadvantages to soil, crop and environment. The objective of the study was to investigate the effect of irrigation with wastewater on soil physical and hydraulic properties of soil, as well as the effect on yield, yield components and irrigation water use efficiency (IWUE) of vegetable crop grown under surface and subsurface drip irrigation systems. Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural field site in Saudi Arabia. A strip plot design (split block) was constructed to maintain six wastewater qualities. Crop water requirement was calculated by Penman Monteith equation for dry land condition. Physical and hydraulic properties of soil were analyzed at pre-season and post-season to quantify the impact of wastewater trea...
The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacter... more The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacteria have not been clearly documented. In the present study, three PHB producers belonging to cyanobacteria were identified as Oscillatoria salina, Anabaena cylindrica and Nostoc linckia, based on their morphological features and microscopic observations. Their growth and PHB production after 7, 14 and 21 days in BG11 medium were determined. The highest dry weight for the isolates was observed at stationary phase (14 days) and PHB accumulation (%, w/w of dry cells) increased with increasing dry weight up to 14 days, then a decline was observed after 21 days. At the stationary phase, cells of O. salina, A. cylindrica and N. linckia accumulated PHB up to 13.62, 11.88 and 10.03% (w/w of dry cells), respectively. The pH values between 8 and 9 were preferred for PHB accumulation. O. salina, A. cylindrica and N. linckia accumulated the highest PHB 17.31, 15.22 and 14.95%, respectively at pH 8. Nitrogen and phosphorus starvation were found stimulatory for PHB accumulation and he highest PHB production was recorded for O. salina, 20.41 and 26.32%, respectively after 14 days of incubation. Electron microscopic analyses of O. salina cells showed the bioplastic accumulation in granule-like structures which was extracted and studied using IRFT analysis. In conclusion, cyanobacteria are capable of synthesizing high poly--hydroxybutyrate (PHB) under stress.
Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultura... more Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant's effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing se...
The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacter... more The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacteria have not been clearly documented. In the present study, three PHB producers belonging to cyanobacteria were identified as Oscillatoria salina, Anabaena cylindrica and Nostoc linckia, based on their morphological features and microscopic observations. Their growth and PHB production after 7, 14 and 21 days in BG11 medium were determined. The highest dry weight for the isolates was observed at stationary phase (14 days) and PHB accumulation (%, w/w of dry cells) increased with increasing dry weight up to 14 days, then a decline was observed after 21 days. At the stationary phase, cells of O. salina, A. cylindrica and N. linckia accumulated PHB up to 13.62, 11.88 and 10.03% (w/w of dry cells), respectively. The pH values between 8 and 9 were preferred for PHB accumulation. O. salina, A. cylindrica and N. linckia accumulated the highest PHB 17.31, 15.22 and 14.95%, respectively at pH 8. Nitrogen and phosphorus starvation were found stimulatory for PHB accumulation and he highest PHB production was recorded for O. salina, 20.41 and 26.32%, respectively after 14 days of incubation. Electron microscopic analyses of O. salina cells showed the bioplastic accumulation in granule-like structures which was extracted and studied using IRFT analysis. In conclusion, cyanobacteria are capable of synthesizing high poly--hydroxybutyrate (PHB) under stress.
. The impact of drought on environmental flow (EF) in 27 catchments of the Indus basin is studied... more . The impact of drought on environmental flow (EF) in 27 catchments of the Indus basin is studied from 1980–2018 using the Indicators of Hydrologic Alterations (IHA). The standardized Precipitation Evapotranspiration Index (SPEI) was systematically propagated from one catchment to another using principal component analysis (PCA). Threshold regression is used to determine the severity of drought (scenario-1) and month (scenario-2) that trigger low flows in the Indus Basin. The impact of drought on low EFs is quantified using the Range of variability analysis (RVA). The hydrological alteration factor (HAF) is calculated for each catchment in the Indus basin. The results show that most of the catchments are vulnerable to drought during the periods 1984–1986, 1991/1992, 1997 to 2003, 2007 to 2008, 2012 to 2013, and 2017 to 2018. On a higher time scale (SPEI-12), drought is more severe in Lower Indus Basin (LIB) than in the Upper Indus Basin (UIB). IHA pointed out that drought significantly impacts the distribution of environmental flow components, particularly extreme low flow (ELF) and low flow (LF). The magnitude and frequency of the ELF and LF events increase as drought severity increases. The threshold regression provided useful insights indicating that moderate drought can trigger ELF and LF at shorter time scales (SPEI-1 and SPEI-6) in the UIB and Middle Indus Basin (MIB). Conversely, severe and extreme drought triggers ELF and LF at higher time scales (SPEI-12) in LIB. The threshold regression also divided the entire study period (1980–2018) into different time zones (scenario-2), which is useful in quantifying the impact of drought on low EFs using the SPEI coefficient. Higher SPEI coefficients are observed in LIB, indicating high alterations in EF due to drought. HAF showed high alterations in EF in most of the catchments throughout the year except in August and September. The alterations are subject to several factors, including climate change, seasonality of the river flow, land use changes, topography, and anthropogenic activities. Overall, this study provided useful insights for analyzing the effects of drought on EF, especially during low flows.
This study aims to comprehend the propagation of meteorological drought (expressed by Standardize... more This study aims to comprehend the propagation of meteorological drought (expressed by Standardized Precipitation Evapotranspiration Index, SPEI) into hydrological drought (expressed by Standardized Runoff Index, SRI) using the combined application of Principal Component Analysis (PCA) and Wavelet analysis for a period of 39-year (1980-2018) in the Indus Basin, Pakistan. PCA was used to calculate principal components of precipitation, temperature, and streamflow, which were used to systematically assess the drought propagation from one catchment to another, resulting in a catchment scale drought assessment. The systematic propagation of drought was useful in capturing the effects of local climate variability in the 27 catchments of the Indus Basin. Wavelet analyses are used to calculate the variability of SPEI/SRI and propagation (analyzed with the wavelet coherence) from SPEI to SRI. The propagation time from SPEI to SRI was cross-correlated. SPEI/SRI time-series showed extreme/seve...
Due to its scarcity, wastewater reuse has become an essential element in water resources and agri... more Due to its scarcity, wastewater reuse has become an essential element in water resources and agriculture planning and management in arid regions. This research aimed to study the effect of irrigation with diluted wastewater on the yield, water use efficiency (WUE), fecal coliform bacteria count, and toxic metals in relation to the root and the fruit of okra and eggplant crops under surface and subsurface drip irrigation systems. A strip plot design (split block) was used in field crop experiments carried out over two consecutive seasons (2011 and 2012) at an agriculture research station in the Western region of Saudi Arabia. The main plot treatments contained six wastewater qualities and two irrigation systems arranged in strips with subplots of 2 × 3 m each. The results showed no significant difference between the two irrigation systems on the fruit yield/ha and WUE of okra, while in eggplant, the subsurface irrigation showed a significant difference. On the other hand, the root to...
Due to aridity, scarcity and unsustainably of natural water resources many developing countries t... more Due to aridity, scarcity and unsustainably of natural water resources many developing countries tend to utilize wastewater for crop production. The use of treated wastewater in irrigation has many advantages and disadvantages to soil, crop and environment. The objective of the study was to investigate the effect of irrigation with wastewater on soil physical and hydraulic properties of soil, as well as the effect on yield, yield components and irrigation water use efficiency (IWUE) of vegetable crop grown under surface and subsurface drip irrigation systems. Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural field site in Saudi Arabia. A strip plot design (split block) was constructed to maintain six wastewater qualities. Crop water requirement was calculated by Penman Monteith equation for dry land condition. Physical and hydraulic properties of soil were analyzed at pre-season and post-season to quantify the impact of wastewater trea...
Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultura... more Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant's effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing se...
Due to its scarcity, wastewater reuse has become an essential element in water resources and agri... more Due to its scarcity, wastewater reuse has become an essential element in water resources and agriculture planning and management in arid regions. This research aimed to study the effect of irrigation with diluted wastewater on the yield, water use efficiency (WUE), fecal coliform bacteria count, and toxic metals in relation to the root and the fruit of okra and eggplant crops under surface and subsurface drip irrigation systems. A strip plot design (split block) was used in field crop experiments carried out over two consecutive seasons (2011 and 2012) at an agriculture research station in the Western region of Saudi Arabia. The main plot treatments contained six wastewater qualities and two irrigation systems arranged in strips with subplots of 2 × 3 m each. The results showed no significant difference between the two irrigation systems on the fruit yield/ha and WUE of okra, while in eggplant, the subsurface irrigation showed a significant difference. On the other hand, the root to...
Due to aridity, scarcity and unsustainably of natural water resources many developing countries t... more Due to aridity, scarcity and unsustainably of natural water resources many developing countries tend to utilize wastewater for crop production. The use of treated wastewater in irrigation has many advantages and disadvantages to soil, crop and environment. The objective of the study was to investigate the effect of irrigation with wastewater on soil physical and hydraulic properties of soil, as well as the effect on yield, yield components and irrigation water use efficiency (IWUE) of vegetable crop grown under surface and subsurface drip irrigation systems. Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural field site in Saudi Arabia. A strip plot design (split block) was constructed to maintain six wastewater qualities. Crop water requirement was calculated by Penman Monteith equation for dry land condition. Physical and hydraulic properties of soil were analyzed at pre-season and post-season to quantify the impact of wastewater trea...
The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacter... more The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacteria have not been clearly documented. In the present study, three PHB producers belonging to cyanobacteria were identified as Oscillatoria salina, Anabaena cylindrica and Nostoc linckia, based on their morphological features and microscopic observations. Their growth and PHB production after 7, 14 and 21 days in BG11 medium were determined. The highest dry weight for the isolates was observed at stationary phase (14 days) and PHB accumulation (%, w/w of dry cells) increased with increasing dry weight up to 14 days, then a decline was observed after 21 days. At the stationary phase, cells of O. salina, A. cylindrica and N. linckia accumulated PHB up to 13.62, 11.88 and 10.03% (w/w of dry cells), respectively. The pH values between 8 and 9 were preferred for PHB accumulation. O. salina, A. cylindrica and N. linckia accumulated the highest PHB 17.31, 15.22 and 14.95%, respectively at pH 8. Nitrogen and phosphorus starvation were found stimulatory for PHB accumulation and he highest PHB production was recorded for O. salina, 20.41 and 26.32%, respectively after 14 days of incubation. Electron microscopic analyses of O. salina cells showed the bioplastic accumulation in granule-like structures which was extracted and studied using IRFT analysis. In conclusion, cyanobacteria are capable of synthesizing high poly--hydroxybutyrate (PHB) under stress.
Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultura... more Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant's effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing se...
The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacter... more The accumulation and factors affecting Poly 3-hydroxybutyric acid (PHB) production in cyanobacteria have not been clearly documented. In the present study, three PHB producers belonging to cyanobacteria were identified as Oscillatoria salina, Anabaena cylindrica and Nostoc linckia, based on their morphological features and microscopic observations. Their growth and PHB production after 7, 14 and 21 days in BG11 medium were determined. The highest dry weight for the isolates was observed at stationary phase (14 days) and PHB accumulation (%, w/w of dry cells) increased with increasing dry weight up to 14 days, then a decline was observed after 21 days. At the stationary phase, cells of O. salina, A. cylindrica and N. linckia accumulated PHB up to 13.62, 11.88 and 10.03% (w/w of dry cells), respectively. The pH values between 8 and 9 were preferred for PHB accumulation. O. salina, A. cylindrica and N. linckia accumulated the highest PHB 17.31, 15.22 and 14.95%, respectively at pH 8. Nitrogen and phosphorus starvation were found stimulatory for PHB accumulation and he highest PHB production was recorded for O. salina, 20.41 and 26.32%, respectively after 14 days of incubation. Electron microscopic analyses of O. salina cells showed the bioplastic accumulation in granule-like structures which was extracted and studied using IRFT analysis. In conclusion, cyanobacteria are capable of synthesizing high poly--hydroxybutyrate (PHB) under stress.
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