scholarly journals Progressive water deficits during multi-year droughts in central-south Chile

2020 ◽  
Author(s):  
Camila Alvarez-Garreton ◽  
Juan Pablo Boisier ◽  
René Garreaud ◽  
Jan Seibert ◽  
Marc Vis
Keyword(s):  
Water Supply ◽  
Arid Regions ◽  
Snow Accumulation ◽  
Annual Rainfall ◽  
General Question ◽  
Runoff Generation ◽  
Water Deficits ◽  
Moderate Drought ◽  
Central South ◽  
Semi Arid

Abstract. A decade-long (2010–2019) period with precipitation deficits in central-south Chile (30–41º S), the so-called megadrought (MD), has led to larger than expected hydrological response and water deficits, indicating an intensification in drought propagation. We used the CAMELS-CL dataset and simulations from the HBV hydrological model to explore the causes of such intensification. Across 124 basins with varying snow/rainfall regimes, we compared annual rainfall-runoff (R-R) relationships and runoff generation mechanisms before and during the MD, and identified those catchments where drought propagation was intensified. We show that catchments’ hydrological memory -mediated by groundwater flows- is a key control of drought propagation intensity, and that baseflow contribution to runoff is positively correlated with snow accumulation preceding the year affected by a drought. Hence, under persistent drought conditions, snow-dominated catchments progressively generate less water, compared with their historical behaviour, notably affecting the semi-arid regions in central Chile. Finally, we addressed a general question: what is worse, an extreme single year drought or a persistent moderate drought? In semi-arid regions, where water provision strongly depends on both the current and previous precipitation seasons, the worst scenario would be an extreme meteorological drought following consecutive years of precipitation below average. In temperate regions of southern Chile, where catchments have more pluvial regimes, hydrologic memory is still an important factor, but water supply is more strongly dependant on the meteorological conditions of the current year, and therefore an extreme drought would have a higher impact on water supply than a persistent but moderate drought.

scholarly journals Progressive water deficits during multiyear droughts in basins with long hydrological memory in Chile

2021 ◽  
Author(s):  
Camila Alvarez-Garreton ◽  
Juan Pablo Boisier ◽  
Rene Garreaud ◽  
Jan Seibert ◽  
Marc Vis
Keyword(s):  
Water Supply ◽  
Meteorological Drought ◽  
Extreme Drought ◽  
General Question ◽  
Central Chile ◽  
Water Demands ◽  
Moderate Drought ◽  
Precipitation Anomalies ◽  
Water Provision ◽  
Central South

<div> <div> <div> <p>A decade-long (2010-2020) period with precipitation deficits in central-south Chile (30-41<sup>o</sup>S), the so-called megadrought (MD), has led to streamflow depletions of larger amplitude than expected from precipitation anomalies, indicating an intensification in drought propagation. We analysed the catchment characteristics and runoff mechanisms modulating such intensification by using the CAMELS-CL dataset and simulations from the HBV hydrological model. We compared annual precipitation-runoff (P-R) relationships before and during the MD across 106 basins with varying snow/rainfall regimes and identified those catchments where drought propagation was intensified.</p> <p>Our results show that catchments’ hydrological memory -modulated by snow and groundwater- is a key control of drought propagation. Snow- dominated catchments (30-35oS) feature larger groundwater contribution to streamflow than pluvial basins, which we relate to the infiltration of snowmelt over the Western Andean Front. This leads to longer memory in these basins, represented by a significative correlation between fall streamflow (when snow has already melted) and the precipitation from the preceding year. Hence, under persistent drought conditions, snow-dominated catchments accumulate the effects of precipitation deficits and progressively generate less water, compared with their historical behaviour, notably affecting central Chile, a region with limited water supply and which concentrates most of the country’s population and water demands. Finally, we addressed a general question: what is worse, an extreme single year drought or a persistent moderate drought? In snow-dominated basins, where water provision strongly depends on both the current and previous precipitation seasons, an extreme drought induces larger absolute streamflow deficits, however persistent deficits induce a more intensified propagation of the meteorological drought. Hence, the worst scenario would be an extreme meteorological drought following consecutive years of precipitation below average, as occurred in 2019. In pluvial basins of southern Chile (35-41<sup>o</sup>S), hydrologic memory is still an important factor, but water supply is more strongly dependant on the meteorological conditions of the current year, and therefore an extreme drought would have a higher impact on water supply than a persistent but moderate drought.</p> </div> </div> </div>

scholarly journals Progressive water deficits during multiyear droughts in basins with long hydrological memory in Chile

2021 ◽  
Vol 25 (1) ◽  
pp. 429-446
Author(s):  
Camila Alvarez-Garreton ◽  
Juan Pablo Boisier ◽  
René Garreaud ◽  
Jan Seibert ◽  
Marc Vis
Keyword(s):  
Water Supply ◽  
Meteorological Drought ◽  
Extreme Drought ◽  
General Question ◽  
Central Chile ◽  
Water Demands ◽  
Moderate Drought ◽  
Precipitation Anomalies ◽  
Water Provision ◽  
Central South

Abstract. A decade-long (2010–2020) period with precipitation deficits in central–south Chile (30–41∘ S), the so-called megadrought (MD), has led to streamflow depletions of larger amplitude than expected from precipitation anomalies, indicating an intensification in drought propagation. We analysed the catchment characteristics and runoff mechanisms modulating such intensification by using the CAMELS-CL dataset and simulations from the HBV hydrological model. We compared annual precipitation–runoff (P–R) relationships before and during the MD across 106 basins with varying snow-/rainfall regimes and identified those catchments where drought propagation was intensified. Our results show that catchments' hydrological memory – modulated by snow and groundwater – is a key control of drought propagation. Snow-dominated catchments (30–35∘ S) feature larger groundwater contribution to streamflow than pluvial basins, which we relate to the infiltration of snowmelt over the Western Andean Front. This leads to longer memory in these basins, represented by a significative correlation between autumn streamflow (when snow has already melted) and the precipitation from the preceding year. Hence, under persistent drought conditions, snow-dominated catchments accumulate the effects of precipitation deficits and progressively generate less water, compared with their historical behaviour, notably affecting central Chile, a region with limited water supply and which concentrates most of the country's population and water demands. Finally, we addressed a general question: what is worse – an extreme single-year drought or a persistent moderate drought? In snow-dominated basins, where water provision strongly depends on both the current and previous precipitation seasons, an extreme drought induces larger absolute streamflow deficits; however persistent deficits induce a more intensified propagation of the meteorological drought. Hence, the worst scenario would be an extreme meteorological drought following consecutive years of precipitation below average, as occurred in 2019. In pluvial basins of southern Chile (35–41∘ S), hydrologic memory is still an important factor, but water supply is more strongly dependant on the meteorological conditions of the current year, and therefore an extreme drought would have a higher impact on water supply than a persistent but moderate drought.

Effects of Genotype and Rainfall on Forage Oats in a Semi-arid Region

1977 ◽  
Vol 13 (3) ◽  
pp. 217-223 ◽  
Author(s):  
A. Hadjichristodoulou
Keyword(s):  
Arid Region ◽  
Selection Criteria ◽  
Crude Protein ◽  
Dry Matter ◽  
Arid Regions ◽  
Correlation Coefficients ◽  
Annual Rainfall ◽  
Varietal Response ◽  
Semi Arid Region ◽  
Semi Arid

SUMMARYThere were significant differences in dry matter yield among five forage oat varieties tested at ten environments during 1970–75. The correlation coefficients between annual rainfall and DM yield varied with variety from 0·69 to 0·88, late varieties tending to give higher yields. Lateness, and high varietal response to annual rainfall and improved environmental conditions, can be used as selection criteria in semi-arid regions. Late varieties had higher DM and lower crude protein contents, and forage produced under lower rainfall conditions tended to have more DM and crude protein.

scholarly journals Water availability and demand in the humid and arid regions within development regions of South Africa

1989 ◽  
Vol 8 (1) ◽  
pp. 9-11
Author(s):  
A. B. De Villiers ◽  
L. A. Van Wyk ◽  
W. Viviers
Keyword(s):  
South Africa ◽  
Water Supply ◽  
Water Availability ◽  
Arid Regions ◽  
Supply And Demand ◽  
Individual Development ◽  
Annual Rainfall ◽  
Great Promise ◽  
Drainage Basins ◽  
Average Annual Rainfall

A method has been developed to distinguish between water supply and demand in individual development regions which contain distinct humid and arid to subarid areas. Development regions A and D have heterogeneous climatic distributions within their borders and are dealt with in this regard. These regions can be divided into arid and humid areas. A magisterial district was considered to be humid when the average annual rainfall is more than 400 mm over more than 50 percent of its total area. The water availability and demand for each of the districts (whether humid or arid) were calculated on a pro rata basis according to the area each district occupies within the various secondary drainage basins. The results obtained in this study show great promise to divide the regions into arid and humid areas for more accurate and detailed planning within the development regions.

Irrigation in semi-arid regions

1967 ◽  
Vol 5 (4) ◽  
pp. 139-143 ◽  
Author(s):  
E. R. Hoare
Keyword(s):  
Water Surface ◽  
Arid Regions ◽  
Living Conditions ◽  
Annual Rainfall ◽  
Land Area ◽  
Semi Arid

A land area can be considered semi-arid if it has an annual rainfall of less than 15 inches and if the evaporation from a water surface exceeds 45 inches. Such areas, under irrigation, can be highly productive agriculturally and can also provide congenial living conditions. The extension of irrigation to new territories could contribute greatly to feeding and clothing the world's population.

Spatial simulation of water supply service flow in Ningxia, China

2020 ◽  
Author(s):  
Jie Xu ◽  
Gaodi Xie ◽  
Yu Xiao ◽  
Jingya Liu ◽  
Keyu Qin ◽  
...  
Keyword(s):  
Water Supply ◽  
River Basin ◽  
Water Conservation ◽  
Arid Regions ◽  
Yellow River ◽  
Source Region ◽  
Regional Scale ◽  
Tibet Plateau ◽  
Residual Water ◽  
Semi Arid

<p>Transregional Ecosystem Service (ES) flows are ubiquitous and are receiving more attention in an increasingly metacoupled world. Water has typical flow properties and is a common flow medium of Water-related Ecosystem Services (WES), such as water supply, water conservation, etc. Ningxia is in a transition zone from semi-arid to arid areas of the Yellow River basin of China. Its role in the water transfer from the Qinghai-Tibet Plateau to the downstream city and agriculture is important in allocating the scarce water resources in (semi-)arid regions. This study described the water flow process to/from Ningxia and revealed the supply-demand balance of water in Ningxia and its adjacent basins. On the grid scale, the total dynamic residual water in Ningxia from 2000 to 2015 was 2.20×10<sup>12</sup> m<sup>3</sup>~6.26×10<sup>12</sup> m<sup>3</sup>. However, there was still a dynamic water demand gap of -72.25×10<sup>8</sup> m<sup>3</sup> ~ -59.08×10<sup>8</sup> m<sup>3</sup>, which could only be supplemented by manual water intake. At the regional scale, Ningxia had two sides, which was both the beneficiary of the upper Xiaheyan basin, Qingshui River - Kushui River basin, Xiaheyan - Shizuishan basin, Hexi Inland River-Shiyang River basin, Hexi Inland Rive-Hexi desert basin and internal flow area, and the supplier of the downstream Shizuishan - Hekou town, Longmen to Sanmenxia subbasin. As the benefitting district, the total net inflow water supply service in the supply area from 2000 to 2015 was 135.86×10<sup>8</sup> m<sup>3 </sup>~ 294.22×10<sup>8</sup> m<sup>3</sup>, among which the non-Ningxia region in the sub-basin above the Xiaheyan basin was the main source region of water supply service in Ningxia. As the supply area, the net outflow volume of water supply service in Ningxia from 2000 to 2015 was 72.83×10<sup>8</sup> m<sup>3</sup>~200.46×10<sup>8</sup> m<sup>3</sup>, mainly flowing to non-Ningxia regions from Shizuishan to Hekou town. Overall, the net volume of water supply service flowing into Ningxia from 2000 to 2015 ranged from 63.03×10<sup>8</sup> m<sup>3</sup> to 93.76×10<sup>8</sup> m<sup>3</sup>. This study can enhance the understanding of trans-boundary telecoupling relationship of WES in Ningxia and contribute to form a foundation for interregional management and allocation of WES in (semi-)arid regions to promote equity in sustainable regional development.</p>

scholarly journals Numerical Investigation for Riverbank Filtration Sustainability Considering Climatic Changes in Arid and Semi-Arid Regions; Case Study of RBF Site at Embaba, Nile Delta, Egypt

2021 ◽  
Vol 13 (4) ◽  
pp. 1897
Author(s):  
Ismail Abd-Elaty ◽  
Hala M. Ghanayem ◽  
Martina Zeleňáková ◽  
Peter Mésároš ◽  
Osama K. Saleh
Keyword(s):  
Water Supply ◽  
Arid Regions ◽  
Nile Delta ◽  
Climatic Changes ◽  
Numerical Code ◽  
Base Case ◽  
Water Supply Systems ◽  
Aquifer Recharge ◽  
Semi Arid

Changes in riverine hydrography and reduced aquifer recharge due to projected climate changes in arid and semi-arid regions are the main issues of water supply, especially in the Nile Delta, Egypt. Continuous degradation results from reduced Nile water flow, poor management of groundwater extraction, and human activities throughout the Nile’s course and drainage channels. Contamination of this water with heavy metals and dissolved organic solids reduces the quality of this water, which increases the price of treatment. River Bank Filtration (RBF) is a water treatment technology used for improving the quality of drinking water taken from polluted rivers where abstraction wells are installed on the banks. This study was applied to the RBF site at Embaba, Nile Delta, Egypt using the numerical code MT3D. The study was simulated and calibrated for the current situation and number of scenarios to investigate the effect of climatic changes on RBF sustainability. Four scenarios were simulated to identify and estimate the RBF portion and the total water travel time from the river to the wells. The first scenario involves a reduction in river stages, the second a decrease in aquifer recharge, the third a combination of the first two scenarios, and the fourth scenario combines scenarios 1, 2, and 3. The results indicate that the RBF portion decreased from 67.42% in the base case to 35.46% and 64.99% with a reduction in river stage by 75% from the base case and a decrease in aquifer recharge from 182.50 (base case) to 50 mm per year, respectively. Moreover, the RBF portion increased to reach 87.75% with a reduction in the General Head Boundary of 75% from the base case, while the combination of the three scenarios decreased the RBF portion to 67.24%. Finally, the water supply systems in arid and semi-arid regions should be extended by installing and operating RBF facilities to manage the negative effects of climatic change through reduction in river stages and aquifer recharge, and increasing abstraction due to overpopulation.

scholarly journals Analysis of trend rainfall: Case of North-Eastern Algeria

2018 ◽  
Vol 36 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Dounia Mrad ◽  
Yassine Djebbar ◽  
Yahia Hammar
Keyword(s):  
Arid Regions ◽  
Winter Season ◽  
Magnitude Estimate ◽  
Annual Rainfall ◽  
Distance Weighting ◽  
North Eastern ◽  
Eastern Algeria ◽  
Annual Scale ◽  
Inverse Distance ◽  
Semi Arid

AbstractThe climatic change is a reality largely recognized today in the scientific community. Nevertheless, its impact on precipitation, especially on annual, monthly and seasonally rainfall in arid and semi-arid regions is not yet certain. Indeed, very few studies have dealt with this matter in Algeria.In this context to examine spatial distribution of annual and seasonal rainfall an attempt has been made using the inverse distance weighting (IDW) method. Trends and magnitude estimate of change in rainfall series were detected by Mann–Kendall tests and Sen's test slope, has been applied to the data registered of 35 stations in the watershed Constantinois Seybouse Mellegue (CSM) North-Eastern Algeria over a period of 43 years (1969–2012).Results from spatial plot of annual rainfall showed that the rainfall increases with altitude, but is higher for the stations exposed to moist winds. It also increases from east to west and conversely decreases as one moves away from the coast to the south. From statistical method showed that there are increase trends at 95% confidence at annual scale in some rainfall stations with high altitude and coastal stations during winter season.

scholarly journals A modified Xinanjiang model and its application in northern China

2005 ◽  
Vol 36 (2) ◽  
pp. 175-192 ◽  
Author(s):  
Caihong Hu ◽  
Shenglian Guo ◽  
Lihua Xiong ◽  
Dingzhi Peng
Keyword(s):  
Arid Regions ◽  
Southern China ◽  
Northern China ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Runoff Simulation ◽  
Xinanjiang Model ◽  
Infiltration Excess ◽  
Semi Arid ◽  
Better Than

The Xinanjiang model has been widely used in the humid regions in southern China as a basic tool for rainfall–runoff simulation, flood forecasting and water resources planning and management. However, its performance in the arid and semi-arid regions of northern China is usually not so good as in the humid regions. A modified Xinanjiang model, in which runoff generation in the watershed is based on both infiltration excess and saturation excess runoff mechanisms, is presented and discussed. Three different watersheds are selected for assessing and comparing the performance of the Xinanjiang model, the modified Xinanjiang model, the VIC model and the TOPMODEL in rainfall–runoff simulation. It is found that the modified Xinanjiang model performs better than the Xinanjiang model, and the models considering the Horton and Dunne runoff generation mechanisms are slightly better than those models considering the single runoff generation mechanism in semi-arid areas. It is suggested that the infiltration excess runoff mechanism should be included in rainfall–runoff models in arid and semi-arid regions.

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