Differences In Water Yield Research Articles

Simulation of Spatial and Temporal Variations in the Water Yield Function in the Source Area of the Yellow River and an Analysis of Influencing Factors

The Yellow River source area is an important eco-fragile and sensitive zone in the northeast of the Tibetan Plateau, where anthropogenic disturbances, climate change, and environmental problems have negatively affected the amount of water in the basin, which directly impacts the ecological security and high-quality sustainable development of the Yellow River Basin. Therefore, this study takes the Yellow River source area as its research area. Based on eight periods of land use from 1985 to 2020, topographic, soil, and meteorological data are combined, and a locally modified InVEST model and geological detector method are used to simulate watershed water production, evaluate the spatial differentiation characteristics of watershed water production, and analyze its spatial heterogeneity attribution. The results revealed that water production from 1985 to 2020 varied within the interval of 152.08–302.44 billion m3, with alternating decreases and increases and an overall upward trend. In the spatial distribution, the depth of water production is high in the east and low in the west, and the high-water-production area is concentrated in the counties of Maqin and Gande. In the vertical gradient, the water production capacity is strengthened with increasing altitudes. The spatial differentiation of the water production service and degree of influence is jointly determined by multiple factors. In this work, the parameter Z of the InVEST model was locally corrected to increase the applicability of the Z value to the Yellow River Basin to improve the accuracy of the simulation results, and the spatiotemporal differences in water yield from multiple perspectives were analyzed to provide a scientific basis for the ecological protection and high-quality sustainable development of the Yellow River Basin.

Extreme weather characteristics and influences on urban ecosystem services in Wuhan Urban Agglomeration

In recent years, there has been a pronounced increase in the frequency of extreme weather events. To comprehensively examine the impact of extreme weather on ecosystem services within the Wuhan Urban Agglomeration (WUA), this study utilized meteorological station data, the Mann-Kendall (MK) test, and the Standardized Precipitation-Evapotranspiration Index (SPEI) to quantify the variation trends in heatwaves (HW) and droughts from 1961 to 2020. Then the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was employed to evaluate and compare the differences in water yield and climate regulation ecosystem services under various HW, droughts, and HW-drought combination scenarios. The results show that over the past 60 years, the temperature, duration, and frequency of HW have significantly increased in the WUA. Specifically, the highest HW temperature, total HW days, HW frequency, and average HW temperature showed changing trend of +0.17 ℃/decade, +1.4 day/decade, +0.19 event/decade, and +0.07 ℃/decade, respectively. The year 2000 was identified as a mutation year for HW, characterized by increased frequency and heightened severity thereafter. The SPEI value exhibited an insignificant upward trend, with 1980 marked as a mutation year, indicating a decreasing trend in drought occurrences after 1980. Heatwaves have a weakening effect on both water yield and climate regulation services, while drought significantly weakened water yield and had a relatively modest effect on climate regulation. During HW-drought composite period, the average monthly water yield showed a notable discrepancy of 60 mm compared to humid years. Besides, as heatwaves intensify, the area of low aggregation for ecosystem services expands, whereas the area of high aggregation decreases. This study provides a preliminary understanding of the impact of urban extreme weather on urban ecosystem services under changing climatic conditions.

Spatio-Temporal Analysis of Water Supply Services in the Li River Basin

The water supply services of the Li River are essential for the ecological environment and local social development. Based on the InVEST model, we quantitatively analyzed the spatial and temporal distribution patterns of water supply services in the Li River Basin from 2000 to 2018 at multiple scales, including the raster, sub-basin, and regional scales, clarified the differences in water yield among different land use types, and explored the different stages of changes in the characteristics of water services. The results revealed four key aspects of this system. (1) The water supply service of Li River Basin showed a spatial distribution pattern of high in the north and low in the south, and the water yield gradually decreased from north to south. (2) Among the various land use types in Li River Basin, the average water supply capacity decreased in the following order: artificial surface, unused land, grassland, forest, cropland and wetland. (3) The average amounts of water services in the 18 sub-basins varied widely, with four sub-basins belonging to the high-value area for water supply services, eight in the middle-value area, and six in the low-value area. (4) From 2000 to 2010, the regions with large fluctuations in water supply services include the midstream region, Lipu River region, and the northern region of Gongcheng River; while from 2010 to 2018, the areas with large fluctuations were in the midstream region and Gongcheng River region. The results of this research increase our understanding of the water supply services in the Li River Basin and provide a critical scientific basis for the reverse compensation of a regional ecological compensation mechanism.

Evaluation of the Effects of Pine Management on the Water Yield and Quality in Southern Brazil

ABSTRACT We evaluated the effects of pine (Pinus taeda L.) thinning and clear-cutting on the water yield and quality of three micro-watersheds from southern Brazil using paired- (reference site) and within-site (pre- and post-management periods) comparisons between 2013 and 2016. We inspected for differences in topographic and remote sensing data between the reference site 1 (native forest) and the managed sites 2 (thinning) and 3 (clear-cutting). Double-mass analysis and analysis of covariance (ANCOVA) were used to evaluate rainfall across sites. Using physicochemical data, we calculated the Water Quality Index (WQI) and measured the water yield, detecting anomalous events with wavelet transform. Finally, we verified differences across- and within-sites in median values of yield and WQI using the non-parametric Mann-Whitney test. The results from paired- and within-site comparisons showed that the management practices did not control the water yield and quality of the three studied micro-watersheds. Statistically significant differences in water yield and WQI were observed between the reference site 1 and pine-planted sites only in the pre-management period. Our findings showed slight differences across sites in morphometric parameters of the watersheds. The ANCOVA confirmed the importance of rainfall in controlling the variability of water yield over the thinning and clear-cutting sites.

Isotopic tracing of hydrologic drivers including permafrost thaw status for lakes across Northeastern Alberta, Canada: A 16-year, 50-lake assessment

Study regionSurveys of stable isotopes of water in 50 boreal lakes were conducted during 2002–2017 as a component of Alberta’s Oil Sands acid sensitivity program in northeastern Alberta. Study focusUsing an isotope mass balance approach, watershed, climatic and isotopic data were applied to estimate evaporation losses and residence time of lakes, as well as to estimate water yield from watersheds. New hydrological insights for the regionSite-specific differences in water yield to 50 lakes over 16 years were found to be controlled by latitudinal gradients in climate, wetland type, lake/watershed configuration and permafrost. 19 plateau watersheds located northeast of Fort McMurray and in the Birch and Caribou Mountains which contained significant permafrost were found to have similar water yield to permafrost-poor watersheds if fen-dominated (159 mm/yr: n = 5 vs. 166 mm/yr; n = 31), and enhanced water yield (405 mm/yr; n = 14) if bog-dominated. Water yield was found to be systematically dependent on permafrost extent, yielding up to several hundred millimetres of additional runoff in bog-dominated systems. Temporal trend analysis indicates systemic momentum of change in hydrologic drivers over the 16-year period, although few are statistically significant. A new conceptual framework is proposed for classification of site-to-site permafrost thaw stage to improve water yield prediction, which is expected to influence lake water quality including observed pH increases noted previously for many lakes in the region.

Assessing Hydrological Ecosystem Services in a Rubber-Dominated Watershed under Scenarios of Land Use and Climate Change

Land use and climate change exert pressure on ecosystems and threaten the sustainable supply of ecosystem services (ESS). In Southeast-Asia, the shift from swidden farming to permanent cash crop systems has led to a wide range of impacts on ESS. Our study area, the Nabanhe Reserve in Yunnan province (PR China), saw the loss of extensive forest areas and the expansion of rubber (Hevea brasiliensis Müll. Arg.) plantations. In this study, we model water yield and sediment export for a rubber-dominated watershed under multiple scenarios of land use and climate change in order to assess how both drivers influence the supply of these ESS. For this we use three stakeholder-validated land use scenarios, varying in their degree of rubber expansion and land management rules. As projected climate change varies remarkably between different climate models, we combined the land use scenarios with datasets of temperature and precipitation changes, derived from nine General Circulation Models (GCMs) of the Fifth Assessment Report of the IPCC (Intergovernmental Panel on Climate Change) in order to model water yield and sediment export with InVEST (Integrated Valuation of Ecosystem Services and Trade-offs). Simulation results show that the effect of land use and land management decisions on water yield in Nabanhe Reserve are relatively minor (4% difference in water yield between land use scenarios), when compared to the effects that future climate change will exert on water yield (up to 15% increase or 13% decrease in water yield compared to the baseline climate). Changes in sediment export were more sensitive to land use change (15% increase or 64% decrease) in comparison to the effects of climate change (up to 10% increase). We conclude that in the future, particularly dry years may have a more pronounced effect on the water balance as the higher potential evapotranspiration increases the probability for periods of water scarcity, especially in the dry season. The method we applied can easily be transferred to regions facing comparable land use situations, as InVEST and the IPCC data are freely available.

Riego capilar por mecha en el cultivo de lechuga (Lactuca sativa L.) en sistema combinado de solución hidropónica y suelo, como alternativa en la agricultura urbana de Bolivia

Algunas de las principales ciudades de Bolivia se encuentran ubicadas en zonas semiáridas y áridas, donde se tiene sequías en forma recurrente que provocan racionamiento en la dotación de agua. El presente estudio fue realizado en el centro Experimental de Cota Cota, dependiente de la Universidad Mayor de San Andrés, ubicado en la ciudad de La Paz a 3400 m.s.n.m. En tal sentido. el objetivo del presente trabajo fue evaluar el riego por mecha en el cultivo de lechuga (Lactuca sativa L.) en sistema combinado de suelo y solución hidropónica, durante dos ciclos de cultivo. Para ello se usaron recipientes desechables de plástico de 5 litros de capacidad. En una parte del envase se puso el sustrato (arena o suelo franco) y en la otra la solución hidropónica (FAO, La Molina y la Local) y mecha de algodón. El consumo de agua por transpiración en los sistemas de riego con y sin mecha fue similar, sin embargo, hubo diferencias altamente significativas en el rendimiento y productividad del agua a favor de la solución FAO, principalmente en el segundo ciclo. En este tipo de sistemas de riego se observó una gran reducción del consumo de agua, además no existe gasto de energía adicional, por lo que se constituye en una alternativa para el cultivo de hortalizas de hoja, en pequeñas superficies de terreno.

Mapping water yield distribution across the South Athabasca Oil Sands (SAOS) area: Baseline surveys applying isotope mass balance of lakes

Study regionSurveys of stable isotopes of water in 121 lakes were conducted between 2007 and 2009 to assist in characterizing baseline hydrology of the South Athabasca Oil Sands area, Alberta, a 35,000 km2 boreal forest region with subdued relief, about 70% wetland cover, and a mosaic of lakes, rivers and buried channel networks. The region, currently under rapid development for in-situ oil sands, was close to baseline conditions at the time of survey. Study focusUsing an isotope mass balance approach, isotope data were applied to estimate water yield to lakes across the region. High-resolution maps were created to illustrate the spatial distribution of water yield and to compare observed patterns to geologic and physiographic features. New hydrological insights for the regionSite-specific differences in water yield were found in relation to geologic and physiographic features. Notably, high water yields were found in lakes underlain by Colorado shale, lower runoff was found in proximity to incised and buried channels. Consistent patterns from year-to-year reveal zones of low runoff which may be more susceptible to development-related impacts including changes in surface/groundwater interaction and pressurization or depressurization of aquifers or formations. The approach may be helpful for informing design of new monitoring programs to ensure runoff variability is considered. Periodic reassessments are recommended to capture potential development and/or climatic change impacts on the water cycle.

Symposium 17. Ecosystem Capacity for Sustaining Long-term Water Supplies

Symposium 17. Ecosystem Capacity for Sustaining Long-term Water Supplies

Differential Snowpack Accumulation and Water Dynamics in Aspen and Conifer Communities: Implications for Water Yield and Ecosystem Function

Early succession aspen and late succession conifer forests have different architecture and physiology affecting hydrologic transfer processes. An evaluation of water pools and fluxes was used to determine differences in the hydrologic dynamics between stands of quaking aspen (Populus tremuloides) and associated stands of mixed conifer consisting of white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), and Engelmann spruce (Picea engelmannii). In 2005 and 2006, measurements of snow water accumulation, snow ablation (melt), soil water content, snowpack sublimation, and evapotranspiration (ET) were measured in adjacent aspen and conifer stands. Peak snow water equivalent (SWE) averaged 34–44% higher in aspen in 2005 (average snow fall) and 2006 (above average snow fall), respectively, whereas snow ablation rates were greater in aspen stands (21 mm day−1) compared to conifer stands (11 mm day−1). When changes in soil water content (due to over-winter snowmelt) were combined with peak snow accumulation in 2006, aspen had greater potential (42–83%) water yield for runoff and groundwater recharge. Snowpack sublimation during the ablation period was not significantly different between meadow, aspen, and conifer sites and comprised less than 5% of the winter precipitation. Extended conifer transpiration in spring and fall did not contribute to large differences in water yield (<28 mm y−1). Summertime ET rates were higher in aspen plots (3.6 mm day−1) than in conifer plots (2.7 mm day−1), and differences in net ET largely reflected soil column porosity. This study shows that the largest differences in annual water yield between aspen and conifer stands result from differences in SWE and net summertime ET. Although SWE and accumulation of water in soil was greater in aspen, it was partly offset by greater net annual ET losses in aspen.

Hydrological processes in small catchments of mountain headwater lakes: The Tatra Mountains

This study evaluates runoff and different methods for the estimation of water balance and runoff genesis in four small alpine catchments, which lie outside the standard network of hydrological and climate networks. These test catchments, whose size ranges between 2.3 and 110 ha, are located above the timberline at elevations between 1,784 and 2,380 m. Their land surfaces consist of lakes, rock formations, debris deposits, and alpine meadows. Hydrological data were collected for the water year 2001. The catchments were instrumented by three automatic weather stations recording global and net solar radiation, air temperature, humidity, precipitation, and soil temperature. Lake water levels were registered with staff gauges and runoff evaluated from water storage calculations. Runoff genesis was investigated by means of chemical tracers (Rhodamine WT and Lithium chloride). Hydrological process estimations were made using standard methods including: the input of precipitation and snowmelt, both potential and actual evaporation, which was estimated by the approaches of Hamon, Priestley-Taylor, Penman and Grindley, and runoff calculated from the lake storage, were compared with results of the conceptual hydrological Brook90 model. The empirical results show that hydrological processes are governed by the temperature-dependent regime of high mountain snowmelt. However, the major differences in water yield and runoff genesis between watersheds were due to differences in the morphologies of the lakes and their basins, the soilvegetation complex, and runoff routing. Evaluating approaches to estimation, Penman’s combination of both aerodynamic and energy balance method provides the best fit to observed data with observed evapotranspiration being 78 to 99% of the potential calculated. The deterministic Brook90 model is effective for precipitation-runoff genesis studies in small headwater catchments. In the L’adové pleso basin predicted and observed water yield show close correlation. The annual sum of actual evapotranspiration calculated by BROOK90 (352 mm) corresponds closely to that estimated by the approach of Penman (386 mm).

Impacts of short-rotation hybrid poplar plantations on regional water yield

Hybrid poplar plantations are being established on northwestern Minnesota farmlands in response to demands for timber, pulp and paper, and as a potential source of biomass energy. The Minnesota Department of Natural Resources estimates that between 30 000 and 40 000 ha of former cropland, and former conservation reserve program (CRP) land that was primarily herbaceous cover, will be converted to tree plantations by 2005. This paper reports the results of a 2-year study of the effects of such land use conversions on water yield for plots within tributary watersheds of the Red River of the North, in northwestern Minnesota. Three 8- and 9-year-old hybrid poplar plantations and three 22- to 34-year-old natural mixed hardwood stands were instrumented to measure precipitation, soil moisture, and soil water chemistry. Climatological observations at these sites were used to estimate potential evapotranspiration. These data were used to apply the GLEAMS model (Knisel, W.G. (Ed.), 1993. GLEAMS: groundwater loading effects of agricultural management systems. UGA-CPES-BAED Publication No. 5, University of Georgia. Coastal Plain Experimental Station, Tifton, GA, 259 pp.) to predict water yield from the two cover types. No significant differences in water yield were detected between hybrid poplar plantations and natural forest stands ( α=0.05). The similarities between the hydrology of these two cover types suggest that increasing the acreage of short-rotation hybrid poplar plantations may influence average peak flows in streams, stormflow during average events, snowmelt runoff and spring flooding in the region.

Large-scale modelling of forest hydrological processes and their long-term effect on water yield

A water balance model was used to simulate the long-term increases in water yield with forest age which are observed in the mountain ash (Eucalyptus regnans) forests of Victoria, Australia. Specifically, the hypothesis was tested that water yield changes could be explained by changes in evapotranspiration resulting from changes in leaf area index (LAI). A curve predicting changes in the total LAI of mountain ash forest was constructed from ground-based observations and their correlation with Landsat Thematic Mapper measurements of the transformed normalized difference vegetation index (TNDVI). A further curve for mountain ash canopy LAI was constructed from destructive LAI measurements and stem diameter measurements. The curves were incorporated within Macaque, a large-scale, physically based water balance model which was applied to three forested catchments (total area 145 km2). The model was used to evaluate the effect of changes in LAI on predicted stream flow over an 82-year period spanning the 1939 wildfires which burnt most of the area. The use of the LAI curves induced improvement in the predicted hydrographs relative to the case for constant LAI, but the change was not large enough to account for all of the difference in water yield between old-growth and regrowth forests. Of a number of possibilities, concomitant changes in leaf conductance with age were suggested as an additional control on stream flow. These were estimated using data on stand sapwood area per unit leaf area and coded into Macaque. The hydrograph predicted using both the LAI curves and a new leaf conductance versus age curve accurately predicted the observed long-term changes in water yield. We conclude that LAI is a partial control on long-term yield changes, but that another ‘water use efficiency per unit LAI’ control is also operative. Copyright © 1999 John Wiley & Sons, Ltd.

Hydrological impacts of converting native forests and grasslands to pine plantations, South Island, New Zealand

Changes in water yield, flood hydrology, and low flows caused by replacing indigenous forests and grasslands with commercial softwoods have been investigated in New Zealand since the mid-1970s. The long-term results of two of these studies are discussed here. The first deals with the conversion of mixed evergreen forest to pine plantation in the northwestern South Island. After a 2-year calibration period one catchment was left as the control (DC2) and the other two catchments were harvested in 1981, one by skidder (DC1) and the other by hauler (DC4), and planted in pines shortly thereafter. For the first 4 years after harvesting the average annual difference in water yields between DC1 and DC2 was 352 mm (69%), and between DC4 and DC2 it was 463 mm (90%), which equates to an annual increase of 312 mm (61%) and 344 mm (68%), respectively, when compared with the calibration period. Planting the harvested areas caused the water yield from both catchments to return to pre-harvesting levels within 8 years, and an estimated reduction in runoff of 340 mm within 5 years at DC4. Mean flood peaks increased after harvesting, especially for small and medium storms on the skidder-logged catchment (75–100%). The response of the storm quickflows to harvesting was similar but much more subdued. Low flows also increased after harvesting. Tree growth brought storm peak flows, quickflows, and low flows back to the levels of those in the original beech forest within 10 years. The second study examines the impact of converting tussock grasslands to pine plantations using data collected from two catchments in the eastern uplands of southern New Zealand. After a 3-year calibration period (1980–1982) one catchment was planted in pines over 67% of its area and the other was left in tussock. By 1989 the difference in annual water yield from the planted catchment was 130 mm, and between 1991 and 1994 it averaged 260 mm (27% of total runoff from the control). Differences in low flows (represented by the minimum annual 7-day mean) showed a similar trend, and suggest that in dry periods, afforestation of tussock grasslands can reduce water yields by 0.18 mm day −1. Higher interception losses from increased canopy evaporation is believed to be the main reason for the reduction in water yield. After 10–12 years of tree growth mean flood peaks had fallen between 55 and 65%, and quickflows had decreased by about 50%.

Streamflow characteristics of physiographic units in the northeast

An analysis was made to determine the amount of annual and seasonal water yield, flow duration, and peak flow frequency for seven major physiographic units in the northeast. AU watersheds (137) in the northeast that were less than 100 square miles in area, that had continuous records from 1940 to 1957, and that were not appreciably affected by regulation and diversion were included in the analysis. In addition, streamflows of four small forested experimental watersheds were compared with average streamflow values of the physiographic units in which they were located. The longest simultaneous record available was for a 3‐year period from 1959 to 1962. Results indicate significant differences in water yield between physiographic units as well as between watersheds within units. Water yields from the small experimental watersheds, although based on a shorter and different period of time, were found to correspond closely with average water yields of their respective physiographic units.