scholarly journals Assessing the impact of rainfall seasonality anomalies on catchment-scale water balance components

2019 ◽  
Author(s):  
Paolo Nasta ◽  
Carolina Allocca ◽  
Roberto Deidda ◽  
Nunzio Romano
Keyword(s):  
Water Balance ◽  
Rainy Season ◽  
Annual Rainfall ◽  
Water Yield ◽  
Dynamic Approach ◽  
Catchment Scale ◽  
Water Balance Components ◽  
Annual Average ◽  
Rainfall Seasonality ◽  
The Impact

Abstract. Water balance components at catchment scale are strongly related to annual rainfall amount. Nonetheless, water resources availability in Mediterranean catchments depends also on rainfall seasonality. Indeed, a high percentage of annual rainfall occurs between late fall and early spring and feeds natural and artificial water reservoirs. This amount of water stored in the mild-rainy season is used to offset rainfall shortages in the hot-dry season (between late spring and early fall). Observed seasonal anomalies in historical records are quite episodic, but an increase of their frequency might exacerbate water stress or water excess if the rainy season shortens or extends its duration, e.g. due to climate change. Hydrological models are useful tools to assess the impact of seasonal anomalies on the water balance components and this study evaluates the sensitivity of water yield, evapotranspiration and groundwater recharge on changes in rainfall seasonality by using the Soil Water Assessment Tool (SWAT) model. The study area is the Upper Alento River Catchment (UARC) in southern Italy where a long time-series of daily rainfall is available from 1920 to 2018. To assess seasonality anomalies, we compare two distinct approaches: a static approach based on the Standardized Precipitation Index (SPI), and a dynamic approach that identifies the rainy season by considering rainfall magnitude, timing, and duration. The former approach rigidly selects three seasonal features, namely rainy, dry, and transition seasons, the latter being occasionally characterized by similar properties to the rainy or dry periods. The dynamic approach, instead, is based on a time-variant duration of the rainy season and enables to corroborate the aforementioned results within a probabilistic framework. A dry seasonal anomaly is characterized by a decrease of 241 mm in annual average rainfall inducing a concurrent decrease of 116 mm in annual average water yield, 60 mm in actual evapotranspiration and 66 mm in groundwater recharge. We show that the Budyko curve is sensitive to the seasonality regime in UARC by questioning the implicit assumption of temporal steady-state between annual average dryness and evaporative index. Although the duration of the rainy season does not exert a major control on water balance, we have been able to identify seasonal-dependent regression equations linking water yield to dryness index over the rainy season.

scholarly journals Assessing the impact of seasonal-rainfall anomalies on catchment-scale water balance components

2020 ◽  
Vol 24 (6) ◽  
pp. 3211-3227 ◽  
Author(s):  
Paolo Nasta ◽  
Carolina Allocca ◽  
Roberto Deidda ◽  
Nunzio Romano
Keyword(s):  
Water Balance ◽  
Rainy Season ◽  
Annual Rainfall ◽  
Water Yield ◽  
Implicit Assumption ◽  
Regression Equations ◽  
Catchment Scale ◽  
Water Balance Components ◽  
Rainfall Seasonality ◽  
The Impact

Abstract. Although water balance components at the catchment scale are strongly related to annual rainfall, the availability of water resources in Mediterranean catchments also depends on rainfall seasonality. Observed seasonal anomalies in historical records are fairly episodic, but an increase in their frequency might exacerbate water deficit or water excess if the rainy season shortens or extends its duration, e.g., due to climate change. This study evaluates the sensitivity of water yield, evapotranspiration, and groundwater recharge to changes in rainfall seasonality by using the Soil Water Assessment Tool (SWAT) model applied to the upper Alento River catchment (UARC) in southern Italy, where a long time series of daily rainfall is available from 1920 to 2018. We compare two distinct approaches: (i) a “static” approach, where three seasonal features (namely rainy, dry, and transition fixed-duration 4-month seasons) are identified through the standardized precipitation index (SPI) and (ii) a “dynamic” approach based on a stochastic framework, where the duration of two seasons (rainy and dry seasons) varies from year to year according to a probability distribution. Seasonal anomalies occur when the transition season is replaced by the rainy or dry season in the first approach and when season duration occurs in the tails of its normal distribution in the second approach. Results are presented within a probabilistic framework. We also show that the Budyko curve is sensitive to the rainfall seasonality regime in UARC by questioning the implicit assumption of a temporal steady state between annual average dryness and the evaporative index. Although the duration of the rainy season does not exert a major control on water balance, we were able to identify season-dependent regression equations linking water yield to the dryness index in the rainy season.

Assessing the impact of rainfall seasonality anomalies on catchment-scale water resources availability

2020 ◽  
Author(s):  
Nunzio Romano ◽  
Carolina Allocca ◽  
Roberto Deidda ◽  
Paolo Nasta
Keyword(s):  
Water Balance ◽  
Groundwater Recharge ◽  
Rainy Season ◽  
Annual Rainfall ◽  
Water Yield ◽  
Implicit Assumption ◽  
Water Balance Components ◽  
Annual Average ◽  
Rainfall Seasonality ◽  
The Impact

<p>Water balance components depend on annual rainfall amount and seasonality in Mediterranean catchments. A high percentage of the annual rainfall occurs between late fall and early spring and feeds natural and artificial water reservoirs. This amount of water stored in the mild-rainy season is used to offset rainfall shortages in the hot-dry season (between late spring and early fall). Observed seasonal anomalies in historical records are quite episodic, but an increase of their frequency might exacerbate water stress or water excess if the rainy season shortens or extends its duration, e.g. due to climate change. Hydrological models are useful tools to assess the impact of seasonal anomalies on the water balance components and this study evaluates the sensitivity of water yield, evapotranspiration and groundwater recharge on changes in rainfall seasonality by using the Soil Water Assessment Tool (SWAT) model. The study area is the Upper Alento River Catchment (UARC) in southern Italy where a long time-series of daily rainfall is available from 1920 to 2018. To assess seasonality anomalies, we compare two approaches: a “static” approach based on the Standardized Precipitation Index (SPI), and a “dynamic” approach that identifies the rainy season by considering rainfall magnitude, timing, and duration. The former approach rigidly selects three seasonal features, namely rainy, dry, and transition seasons, the latter being occasionally characterized by similar properties to the rainy or dry periods. The “dynamic” approach, instead, is based on a time-variant duration of the rainy season and enables to corroborate the aforementioned results within a probabilistic framework. A dry seasonal anomaly is characterized by a decrease of 241 mm in annual average rainfall inducing a concurrent decrease of 116 mm in annual average water yield, 60 mm in actual evapotranspiration and 66 mm in groundwater recharge. We show that the Budyko curve is sensitive to the seasonality regime in UARC by questioning the implicit assumption of temporal steady-state between annual average dryness and evaporative index. Although the duration of the rainy season does not exert a major control on water balance, we have been able to identify seasonal-dependent regression equations linking water yield to dryness index over the rainy season.</p>

scholarly journals Evaluation of Different Objective Functions Used in the SUFI-2 Calibration Process of SWAT-CUP on Water Balance Analysis: A Case Study of the Pursat River Basin, Cambodia

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2901
Author(s):  
Davy Sao ◽  
Tasuku Kato ◽  
Le Hoang Tu ◽  
Panha Thouk ◽  
Atiqotun Fitriyah ◽  
...  
Keyword(s):  
Water Balance ◽  
River Basin ◽  
Swat Model ◽  
Water Yield ◽  
Objective Functions ◽  
Water Balance Components ◽  
Annual Average ◽  
Calibration Process ◽  
Fitted Parameter ◽  
Parameter Values

Many calibration techniques have been developed for the Soil and Water Assessment Tool (SWAT). Among them, the SWAT calibration and uncertainty program (SWAT-CUP) with sequential uncertainty fitting 2 (SUFI-2) algorithm is widely used and several objective functions have been implemented in its calibration process. In this study, eight different objective functions were used in a calibration of stream flow of the Pursat River Basin of Cambodia, a tropical monsoon and forested watershed, to examine their influences on the calibration results, parameter optimizations, and water resources estimations. As results, many objective functions performed better than satisfactory in calibrating the SWAT model. However, different objective functions defined different fitted values and sensitivity rank of the calibrated parameters, except Nash–Sutcliffe efficiency (NSE) and ratio of standard deviation of observations to root mean square error (RSR) which are equivalent and produced quite identical simulation results including parameter sensitivity and fitted parameter values, leading to the same water balance components and water yields estimations. As they generated reasonable fitted parameter values, either NSE or RSR gave better estimation results of annual average water yield and other water balance components such as annual average evapotranspiration, groundwater flow, surface runoff, and lateral flow according to the characteristics of the river basin and the results and data of previous studies. Moreover, either of them was also better in calibrating base flow, falling limb, and overall the entire flow phases of the hydrograph in this area.

scholarly journals Variations of global and continental water balance components as impacted by climate forcing uncertainty and human water use

2016 ◽  
Vol 20 (7) ◽  
pp. 2877-2898 ◽  
Author(s):  
Hannes Müller Schmied ◽  
Linda Adam ◽  
Stephanie Eisner ◽  
Gabriel Fink ◽  
Martina Flörke ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Balance ◽  
Water Use ◽  
Climate Forcing ◽  
Land Area ◽  
Water Balance Components ◽  
Climate Forcings ◽  
The Impact ◽  
Global Water

Abstract. When assessing global water resources with hydrological models, it is essential to know about methodological uncertainties. The values of simulated water balance components may vary due to different spatial and temporal aggregations, reference periods, and applied climate forcings, as well as due to the consideration of human water use, or the lack thereof. We analyzed these variations over the period 1901–2010 by forcing the global hydrological model WaterGAP 2.2 (ISIMIP2a) with five state-of-the-art climate data sets, including a homogenized version of the concatenated WFD/WFDEI data set. Absolute values and temporal variations of global water balance components are strongly affected by the uncertainty in the climate forcing, and no temporal trends of the global water balance components are detected for the four homogeneous climate forcings considered (except for human water abstractions). The calibration of WaterGAP against observed long-term average river discharge Q significantly reduces the impact of climate forcing uncertainty on estimated Q and renewable water resources. For the homogeneous forcings, Q of the calibrated and non-calibrated regions of the globe varies by 1.6 and 18.5 %, respectively, for 1971–2000. On the continental scale, most differences for long-term average precipitation P and Q estimates occur in Africa and, due to snow undercatch of rain gauges, also in the data-rich continents Europe and North America. Variations of Q at the grid-cell scale are large, except in a few grid cells upstream and downstream of calibration stations, with an average variation of 37 and 74 % among the four homogeneous forcings in calibrated and non-calibrated regions, respectively. Considering only the forcings GSWP3 and WFDEI_hom, i.e., excluding the forcing without undercatch correction (PGFv2.1) and the one with a much lower shortwave downward radiation SWD than the others (WFD), Q variations are reduced to 16 and 31 % in calibrated and non-calibrated regions, respectively. These simulation results support the need for extended Q measurements and data sharing for better constraining global water balance assessments. Over the 20th century, the human footprint on natural water resources has become larger. For 11–18% of the global land area, the change of Q between 1941–1970 and 1971–2000 was driven more strongly by change of human water use including dam construction than by change in precipitation, while this was true for only 9–13 % of the land area from 1911–1940 to 1941–1970.

scholarly journals GEO-CWB: GIS-Based Algorithms for Parametrising the Responses of Catchment Dynamic Water Balance Regarding Climate and Land Use Changes

Hydrology ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 39 ◽  
Author(s):  
Salem S. Gharbia ◽  
Laurence Gill ◽  
Paul Johnston ◽  
Francesco Pilla
Keyword(s):  
Land Use ◽  
Water Balance ◽  
Land Use Changes ◽  
Critical Factor ◽  
Balance Model ◽  
Spatial And Temporal Patterns ◽  
Catchment Scale ◽  
Water Balance Components ◽  
Spatially Distributed ◽  
Hydrological System

Parametrising the spatially distributed dynamic catchment water balance is a critical factor in studying the hydrological system responses to climate and land use changes. This study presents the development of a geographic information system (GIS)-based set of algorithms (geographical spatially distributed water balance model (GEO-CWB)), which is developed from integrating physical, statistical, and machine learning models. The GEO-CWB tool has been developed to simulate and predict future spatially distributed dynamic water balance using GIS environment at the catchment scale in response to the future changes in climate variables and land use through a user-friendly interface. The tool helps in bridging the gap in quantifying the high-resolution dynamic water balance components for the large catchments by reducing the computational costs. Also, this paper presents the application and validation of GEO-CWB on the Shannon catchment in Ireland as an example of a large and complicated hydrological system. It can be concluded that climate and land use changes have significant effects on the spatial and temporal patterns of the different water balance components of the catchment.

scholarly journals The Impact of Para Rubber Expansion on Streamflow and Other Water Balance Components of the Nam Loei River Basin, Thailand

Water ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
Winai Wangpimool ◽  
Kobkiat Pongput ◽  
Nipon Tangtham ◽  
Saowanee Prachansri ◽  
Philip Gassman
Keyword(s):  
Water Balance ◽  
River Basin ◽  
Water Balance Components ◽  
The Impact

scholarly journals Forecasting land-use change and its impact on the groundwater system of the Kleine Nete catchment, Belgium

2007 ◽  
Vol 4 (6) ◽  
pp. 4265-4295 ◽  
Author(s):  
J. Dams ◽  
S. T. Woldeamlak ◽  
O. Batelaan
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Water Balance ◽  
Groundwater Level ◽  
Balance Model ◽  
Groundwater Model ◽  
Water Balance Components ◽  
Groundwater System ◽  
The Impact

Abstract. Land-use change and climate change, along with groundwater pumping are frequently indicated to be the main human-induced factors influencing the groundwater system. Up till now, research has mainly been focusing on the effect of the water quality of these human-induced changes on the groundwater system, often neglecting changes in quantity. The focus in this study is on the impact of land-use changes in the near future, from 2000 until 2020, on the groundwater quantity and the general hydrologic balance of a sub-catchment of the Kleine Nete, Belgium. This study tests a new methodology which involves coupling a land-use change model with a water balance model and a groundwater model. The future land-use is modelled with the CLUE-S model. Four scenarios (A1, A2, B1 and B2) based on the Special Report on Emission Scenarios (SRES) are used for the land-use modelling. Water balance components, groundwater level and baseflow are simulated using the WetSpass model in conjunction with a MODFLOW groundwater model. Results show that the average recharge slowly decreases for all scenarios, the decreases are 2.9, 1.6, 1.8 and 0.8% for respectively scenario A1, A2, B1 and B2. The predicted reduction in recharge results in a small decrease of the average groundwater level, ranging from 2.5 cm for scenario A1 to 0.9 cm for scenario B2, and a reduction of the total baseflow with maximum 2.3% and minimum 0.7% respectively for scenario A1 and B2. Although these average values do not indicate significant changes for the groundwater system, spatial analysis of the changes shows the changes are concentrated in the neighbourhood of the major cities in the study areas. It is therefore important for spatial managers to take the groundwater system into account for reducing the negative impacts of land-use and climate change as much as possible.

Estimation of Spatial and Temporal Groundwater Balance Components in Khadir Canal Sub-Division, Chaj Doab, Pakistan

Hydrology ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 178
Author(s):  
Muhammad Aslam ◽  
Ali Salem ◽  
Vijay P. Singh ◽  
Muhammad Arshad
Keyword(s):  
Land Use ◽  
Water Balance ◽  
Groundwater Recharge ◽  
Groundwater Resources ◽  
Balance Model ◽  
Annual Rainfall ◽  
Water Balance Components ◽  
Aquifer Management ◽  
Groundwater Balance ◽  
Semi Arid

Evaluation of the spatial and temporal distribution of water balance components is required for efficient and sustainable management of groundwater resources, especially in semi-arid and data-poor areas. The Khadir canal sub-division, Chaj Doab, Pakistan, is a semi-arid area which has shallow aquifers which are being pumped by a plethora of wells with no effective monitoring. This study employed a monthly water balance model (water and energy transfer among soil, plants, and atmosphere)—WetSpass-M—to determine the groundwater balance components on annual, seasonal, and monthly time scales for a period of the last 20 years (2000–2019) in the Khadir canal sub-division. The spatial distribution of water balance components depends on soil texture, land use, groundwater level, slope, and meteorological conditions. Inputs for the model included data on topography, slope, soil, groundwater depth, slope, land use, and meteorological data (e.g., precipitation, air temperature, potential evapotranspiration, and wind speed) which were prepared using ArcGIS. The long-term average annual rainfall (455.7 mm) is distributed as 231 mm (51%) evapotranspiration, 109.1 mm (24%) surface runoff, and 115.6 mm (25%) groundwater recharge. About 51% of groundwater recharge occurs in summer, 18% in autumn, 14% in winter, and 17% in spring. Results showed that the WetSpass-M model properly simulated the water balance components of the Khadir canal sub-division. The WetSpass-M model’s findings can be used to develop a regional groundwater model for simulation of different aquifer management scenarios in the Khadir area, Pakistan.

Changes in water flows and water productivity upon vegetation regeneration on degraded hillslopes in northern Ethiopia: a water balance modelling exercise

2009 ◽  
Vol 31 (2) ◽  
pp. 237 ◽  
Author(s):  
Katrien Descheemaeker ◽  
Dirk Raes ◽  
Jan Nyssen ◽  
Jean Poesen ◽  
Mitiku Haile ◽  
...  
Keyword(s):  
Water Balance ◽  
Biomass Production ◽  
Water Conservation ◽  
Root Zone ◽  
Water Productivity ◽  
Annual Rainfall ◽  
Northern Ethiopia ◽  
Water Balance Components ◽  
Water Flows ◽  
Vegetation Regeneration

The establishment of exclosures (i.e. areas closed for grazing and agriculture) is a common practice to reverse land degradation through vegetation regeneration in the semiarid highland areas of northern Ethiopia. In order to assess the effect of exclosures on water flows, the water balance components for different vegetation regeneration stages were assessed through field measurements and modelling. Successful model calibration and validation was done based on soil water content measurements conducted during 2 years in 22 experimental plots. In the protected areas, vegetation regeneration leads to an increase in infiltration and transpiration and a more productive use of water for biomass production. In areas where additional lateral water (runon) infiltrates, source–sink systems are created. Here, up to 30% of the annual rainfall percolates through the root-zone towards the groundwater table. Increased biomass production in exclosures leads to possibilities for wood harvesting and cut and carry of grasses for livestock feeding. Together with water conservation and more productive use of water, the latter contributes to increased livestock water productivity. At the landscape scale, the creation of vegetation filters, capturing resources like water and nutrients, reinforces the rehabilitation process and healthy landscape functioning.

scholarly journals Potential climate change impacts on the water balance of regional unconfined aquifer systems in south-western Australia

2012 ◽  
Vol 16 (12) ◽  
pp. 4581-4601 ◽  
Author(s):  
R. Ali ◽  
D. McFarlane ◽  
S. Varma ◽  
W. Dawes ◽  
I. Emelyanova ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Western Australia ◽  
Climate Change Impacts ◽  
Unconfined Aquifer ◽  
Annual Rainfall ◽  
Historical Period ◽  
Confined Systems ◽  
Water Balance Components ◽  
Aquifer Systems

Abstract. This study assesses climate change impacts on water balance components of the regional unconfined aquifer systems in south-western Australia, an area that has experienced a marked decline in rainfall since the mid 1970s and is expected to experience further decline due to global warming. Compared with the historical period of 1975 to 2007, reductions in the mean annual rainfall of between 15 and 18 percent are expected under a dry variant of the 2030 climate which will reduce recharge rates by between 33 and 49 percent relative to that under the historical period climate. Relative to the historical climate, reductions of up to 50 percent in groundwater discharge to the ocean and drainage systems are also expected. Sea-water intrusion is likely in the Peel-Harvey Area under the dry future climate and net leakage to confined systems is projected to decrease by up to 35 percent which will cause reduction in pressures in confined systems under current abstraction. The percentage of net annual recharge consumed by groundwater storage, and ocean and drainage discharges is expected to decrease and percentage of net annual recharge consumed by pumping and net leakage to confined systems to increase under median and dry future climates. Climate change is likely to significantly impact various water balance components of the regional unconfined aquifer systems of south-western Australia. We assess the quantitative climate change impact on the different components (the amounts) using the most widely used GCMs in combination with dynamically linked recharge and physically distributed groundwater models.

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