Impacts of land use changes and climate variability on transboundary Hirmand River using SWAT

Hajihosseini, Mohammadreza; Hajihosseini, Hamidreza; Morid, Saeed; Delavar, Majid; Booij, Martijn J.

doi:10.2166/wcc.2019.100

Cited by 20 publications

(15 citation statements)

References 33 publications

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“…simultaneously using E NS,Q and E NS,log(Q) as calibration objectives to ensure good representation of both high and low flows, our model performances with respect to daily flow in all sub-basins (Table 4, Fig. 4) exceed those of the studies of Hajihosseini et al (2016) but also those of Hajihosseini et al (2019), who assessed the monthly flow with the SWAT model in the upper and lower Helmand basins, respectively.…”

Section: Model Performancementioning

confidence: 83%

“…2). More than 200 km 2 of the increase in the irrigated area is due to the conversion of seasonal grasslands to high-water-requirement poppy cultivation since the 1990s (Hajihosseini et al, 2019). By 2006 around 690 km 2 in the HRB was used for poppy cultivation (UNODC, 2006).…”

Section: Study Areamentioning

confidence: 99%

“…Here, the effects of the reservoirs were estimated with a simple water-accounting scheme based on elevation-storage and elevation-area relationships provided in a study by Vining and Vecchia (2007) and similar to previous work (e.g., Hanasaki et al, 2006;Wisser et al, 2010):…”

Section: Reservoir Routingmentioning

confidence: 99%

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Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Roodari

Hrachowitz

Hassanpour

et al. 2021

Hydrol. Earth Syst. Sci.

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Abstract. The transboundary Helmand River basin (HRB) is the main drainage system for large parts of Afghanistan and the Sistan region of Iran. Due to the reliance of this arid region on water from the Helmand River, a better understanding of hydrological-drought pattern and the underlying drivers in the region is critically required for effective management of the available water. The objective of this paper is therefore to analyze and quantify spatiotemporal pattern of drought and the underlying processes in the study region. More specifically we test for the Helmand River basin the following hypotheses for the 1970–2006 period: (1) drought characteristics, including frequency and severity, systematically changed over the study period; (2) the spatial pattern and processes of drought propagation through the Helmand River basin also changed; and (3) the relative roles of climate variability and human influence on changes in hydrological droughts can be quantified. It was found that drought characteristics varied throughout the study period but largely showed no systematic trends. The same was observed for the time series of drought indices SPI (standard precipitation index) and SPEI (standardized precipitation evapotranspiration index), which exhibited considerable spatial coherence and synchronicity throughout the basin, indicating that, overall, droughts similarly affect the entire HRB with few regional or local differences. In contrast, analysis of the SDI (streamflow drought index) exhibited significant negative trends in the lower parts of the basin, indicating an intensification of hydrological droughts. It could be shown that with a mean annual precipitation of ∼ 250 mm yr−1, streamflow deficits and thus hydrological drought throughout the HRB are largely controlled by precipitation deficits, whose annual anomalies on average account for ±50 mm yr−1, or ∼ 20 % of the water balance of the HRB, while anomalies of total evaporative fluxes on average only account for ±20 mm yr−1. Assuming no changes in the reservoir management practices over the study period, the results suggest that the two reservoirs in the HRB only played a minor role for the downstream propagation of streamflow deficits, as indicated by the mean difference between inflow and outflow during drought periods, which did not exceed ∼ 0.5 % of the water balance of the HRB. Irrigation water abstraction had a similarly limited effect on the magnitude of streamflow deficits, accounting for ∼ 10 % of the water balance of the HRB. However, the downstream parts of the HRB moderated the further propagation of streamflow deficits and associated droughts because of the minor effects of reservoir operation and very limited agricultural water in the early decades of the study period. This drought moderation function of the lower basin was gradually and systematically inverted by the end of the study period, when the lower basin eventually amplified the downstream propagation of flow deficits and droughts. Our results provide plausible evidence that this shift from drought moderation to drought amplification in the lower basin is likely a consequence of increased agricultural activity and the associated increases in irrigation water demand, from ∼ 13 mm yr−1 at the beginning of the study period to ∼ 23 mm yr−1 at the end, and thus in spite of being only a minor fraction of the water balance. Overall the results of this study illustrate that flow deficits and the associated droughts in the HRB clearly reflect the dynamic interplay between temporally varying regional differences in hydro-meteorological variables together with subtle and temporally varying effects linked to direct human intervention.

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Section: Model Performancementioning

confidence: 83%

Section: Study Areamentioning

confidence: 99%

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Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Roodari

Hrachowitz

Hassanpour

et al. 2021

Hydrol. Earth Syst. Sci.

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“…Čerkasova et al (2018) applied the SWAT model to assess the impact of climate change hydrology and water quality in a transboundary river, Nemunas River in Europe. Hajihosseini et al (2020) also used the SWAT model to analyze the impacts of land use changes and climate variability on the transboundary Hirmand River of Afghanistan. Similarly, the model has been extensively applied in the Lower Mekong Region to investigate the impact of climate change, land use change and demographic change on the hydrology and water quality (Oeurng et al 2016;Trang et al 2017).…”

Section: Hydrological Modelingmentioning

confidence: 99%

Assessment of climate change impact on hydrology of a transboundary river of Bhutan and India

Zam

Shrestha

Budhathoki

2021

Journal of Water and Climate Change

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Assessing the impacts of climate change on a transboundary river plays an important role in sustaining water security within as well as beyond the national boundaries. At times, the unilateral decision taken by one country can increase the risk of negative effect on the riparian countries and if the impact is felt strongly by the other country, it can lead to international tension between them. This study examines the impact of climate change on hydrology between a shared river which is Wangchu river in Bhutan and Raidak river in India. The river is mainly used to produce hydropower in the two largest hydropower plants on which the majority of Bhutan's economic development depends and is mainly used for agriculture in India. The Soil and Water Assessment Tool (SWAT) was used for future flow simulation. Future climate was projected for near future (NF) from 2025–2050 and far future (FF) from 2074–2099 using an ensemble of three regional climate models (ACCESS, CNRM-CM5 and MPI-ESM-LR) for two RCPs (Representative Concentration Pathways), RCP 4.5 and RCP 8.5 scenario. The ensemble results indicated that, in future, the study area would become warmer with temperature increase of 1.5 °C under RCP 4.5 and 3.6 °C under RCP 8.5. However, as per RCP 4.5 and RCP 8.5, rainfall over the study area is projected to decrease by 1.90% and 1.38% respectively. As a consequence of the projected decrease in rainfall, the flow in river is projected to decrease by 5.77% under RCP 4.5 and 4.73% under RCP 8.5. Overall, the results indicated that the degree of hydrological change is expected to be higher, particularly for low flows in both Wangchu and Raidak River. Since transboundary water is a shared for economic growth, climate change adaptation and opportunities should also be considered by both the nations for better water management.

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“…While the irrigated area in the LARB remained somewhat stable at around 370 km 2 (~ 0.3 % of the total HRB) over the last decades, satellite imagery (Landsat 7, ETM+) shows that the total irrigated area in the LHRB more than doubled from < 800 km 2 (0.8 %) in the late 1970s to 1650 km 2 (1.6 %) in 2011 (Figure 2). More than 200 km 2 of the increase in irrigated area are due to the conversion of seasonal grasslands to high-water-requirement poppy cultivation since the 1990s (Hajihosseini et al, 2019). By 2006 around 690 km 2 in the HRB were used for poppy cultivation (UNODC, 2006).…”

Section: Study Areamentioning

confidence: 99%

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian River: the individual roles of climate variability and land use change

Roodari¹,

Hrachowitz²,

Hassanpour³

et al. 2020

Preprint

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Abstract. The transboundary Helmand River basin is the main drainage system for large parts of Afghanistan and the Sistan region of Iran. Due to the reliance of this arid region on water from the Helmand River, a better understanding of hydrological drought pattern and the underlying drivers in the region are critically required for an effective management of the available water. The objective of this paper is therefore to analyse and quantify spatio-temporal pattern of drought and the underlying processes in the study region. More specifically we test for the Helmand River Basin the following hypotheses for the 1970–2006 period: (1) drought characteristics, including frequency and severity systematically changed over the study period, (2) the spatial pattern and processes of drought propagation through the Helmand River Basin also changed and (3) the relative roles of climate variability and human influence on changes in hydrological droughts can be quantified. It was found that drought characteristics varied throughout the study period, but did largely show no systematic trends. The same was observed for the time series of drought indices SPI and SPEI, which exhibited considerable spatial coherence and synchronicity throughout the basin indicating that, overall, droughts similarly affect the entire HRB with little regional or local differences. In contrast, analysis of SDI exhibited significant negative trends in the lower parts of the basin, indicating an intensification of hydrological droughts. It could be shown that with a mean annual precipitation of ~250 mm y-1, streamflow deficits and thus hydrological drought throughout the HRB are largely controlled by precipitation deficits, whose annual anomalies on average account for ±50 mm y-1 or ~20 % of the water balance of the HRB, while anomalies of total evaporative fluxes on average only account for ±20 mm y-1. The two reservoirs in the HRB only played a minor role for the downstream propagation of streamflow deficits, as indicated by the mean difference between inflow and outflow during drought periods which did not exceed ~0.5 % of the water balance of the HRB. Irrigation water abstraction had a similarly limited effect on the magnitude of streamflow deficits, accounting for ~10 % of the water balance of the HRB. However, the downstream parts of the HRB moderated the further propagation of streamflow deficits and associated droughts in the early decades of the study period. This drought moderation function of the lower basin was gradually and systematically inverted by the end of the study period, when the lower basin eventually amplified the downstream propagation of flow deficits and droughts. This shift from drought moderation to drought amplification in the lower basin is likely a consequence of increased agricultural activity and the associated increases in irrigation water demand from ~13 mm y-1 at the beginning of the study period to ~23 mm y-1 at the end and thus in spite of being only a minor fraction of the water balance. Overall the results of this study illustrate that flow deficits and the associated droughts in the HRB clearly reflect the dynamic interplay between temporally varying regional differences in hydro-meteorological variables together with subtle and temporally varying effects linked to direct human intervention.

show abstract

Impacts of land use changes and climate variability on transboundary Hirmand River using SWAT

Cited by 20 publications

References 33 publications

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Assessment of climate change impact on hydrology of a transboundary river of Bhutan and India

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian River: the individual roles of climate variability and land use change

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