Surface Water Volume Research Articles

The impact of climate change and human activities on the Aral Sea Basin over the past 50 years

The destruction of the Aral Sea area constitutes one of the world's most infamous ecological disaster. However, the retreat of the Aral Sea has slowed down in recent years and the underlying reasons are not reported. In this work, based on the extreme-point symmetric mode decomposition (ESMD) method and the multiple linear regression model, we analyzed the changing of the Aral Sea from 1960 to 2018, and detected the time for slowdown of retreat, then explored the driving forces. The results show that the Aral Sea retreated rapidly from 1960 to 2004, and the shrinking rates of water surface area, water volume and water level were 1087.00 km2/year, 25.07 km3/year, and 0.56 m/year, respectively; the retreat has slowed since 2005, with the shrinking rates being 760.00 km2/year, 2.86 km3/year, and 0.38 m/year, respectively. At the same time, the area of water bodies surrounding the Aral Sea increased due to the agricultural drainage water. The oscillation periods of water level in the Aral Sea are 2.1a, 7.6a and 29.5a, of which 29.5a is the main period of oscillation. The trend residual RES indicates that water level shows a non-linear downward trend, and the degree of fluctuation has decreased significantly after 2005. The impact of human activities on the Aral Sea is more significant than that of climate change. Overall, the increased upstream runoff, reduced water withdrawal, and rise in water delivery to the Aral Sea has led to a slowing down of the sea's notorious shrinkage. The findings provide a scientific reference for the management and protection of the Aral Sea.

The Lake Chad hydrology under current climate change

Lake Chad, in the Sahelian zone of west-central Africa, provides food and water to ~50 million people and supports unique ecosystems and biodiversity. In the past decades, it became a symbol of current climate change, held up by its dramatic shrinkage in the 1980s. Despites a partial recovery in response to increased Sahelian precipitation in the 1990s, Lake Chad is still facing major threats and its contemporary variability under climate change remains highly uncertain. Here, using a new multi-satellite approach, we show that Lake Chad extent has remained stable during the last two decades, despite a slight decrease of its northern pool. Moreover, since the 2000s, groundwater, which contributes to ~70% of Lake Chad’s annual water storage change, is increasing due to water supply provided by its two main tributaries. Our results indicate that in tandem with groundwater and tropical origin of water supply, over the last two decades, Lake Chad is not shrinking and recovers seasonally its surface water extent and volume. This study provides a robust regional understanding of current hydrology and changes in the Lake Chad region, giving a basis for developing future climate adaptation strategies.

Effects of Sunlight on the Formation Potential of Dichloroacetonitrile and Bromochloroacetonitrile from Wastewater Effluents

Sunlight plays an important role in transforming effluent organic matter as wastewater effluents travel downstream, but the corresponding effects on the formation of haloacetonitriles (HANs), a group of toxic disinfection byproducts, in wastewater-impacted surface water has not been thoroughly investigated. In this study, we observed that sunlight preferentially attenuated the formation potential of bromochloroacetonitrile (BCAN-FP) over that of dichloroacetonitrile (DCAN-FP) in chlorine- and UV-disinfected secondary effluents. For four effluent samples from different plants, 36 h irradiation by simulated sunlight removed 28%-33% of DCAN-FP and 41%-48% of BCAN-FP. Across a larger set of effluent samples (n = 18), 8 h irradiation (equivalent to 2-3 d of natural sunlight) decreased the calculated cytotoxicity contributed by dihaloacetonitrile-FP in most samples. Similar behavior was observed for a mixture of wastewater and surface water (volume ratio 1:1). For UV-disinfected effluents, the higher the UV dose, the more likely was there a reduction in DCAN-FP and BCAN-FP in the subsequent sunlight irradiation. Experiments with model compounds showed that fulvic acid and UV photoproducts of tryptophan yield excited triplet state organic matters during sunlight irradiation and play an important role in promoting the attenuation of HAN precursors.

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

Abstract. Petermann Fjord is a deep (>1000 m) fjord that incises the coastline of north-west Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5 and 70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line kilometres of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to bedrock or till surfaces (Facies I), subglacial deposition (Facies II), deposition from meltwater plumes and icebergs in quiescent glacimarine conditions (Facies III, IV), deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V) and the redeposition of material downslope (Facies IV). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann ice stream as 1080–1420 m3 a−1 per metre of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a−1. Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system, and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in rates over a glacial–deglacial transition. Our new glacial sediment fluxes and erosion rates show that the Petermann ice stream was approximately as efficient as the palaeo-Jakobshavn Isbræ at eroding, transporting and delivering sediment to its margin during early deglaciation.

Water Consumption by Hydropower, Does It Worth Allocation under Ethiopian Context

The Ethiopian water policy strictly follows water allocation as a principle in setting out water consumption problems and demand projection. Hydroelectric power plants supply the larger share (88%) of the electricity in Ethiopia. 86% of Ethiopia’s plan to 2020 energy supply is expected to be from hydropower. This paper defines water consumption in hydropower production as the quantity of water that leaves the analyzed projects (reservoir regulated hydropower projects) through evaporation. Water consumed by hydropower development has never been studied at a country scale. Thus, in attempting to understand water consumption by the hydropower development, this study will be the first to acknowledge the water consumption by all storage regulated hydropower plants developed in Ethiopia. While studying and designing reservoir regulated hydropower production, the overall effect of water consumption by the projects is assumed to be minimal; thus ignoring water allocation to hydropower projects is a common procedure in Ethiopia. In this study, for multipurpose projects, to identify the water consumption by hydropower against the other purpose (irrigation) consumption, water consumption factors based on economic benefits were used. The study has shown that the 14 existing and under construction reservoir regulated hydropower projects will consume 1.881 billion m3 of water annually. This will make hydropower the second most water consuming water resource development next to Irrigation in the country. Together with the 22 upcoming projects the water consumption will be 3.756 billion m3/year. The results also show that hydropower consumption in the country will take an average of 2.41% of the total water stored in a reservoir. This value is in the range of nearly zero for power projects that use natural lakes as their reservoir (Tana Beles, Tis Abay I & II) and GERD to 10.64%. The total reservoir volume that will be created in the country after completion of the 22 planned projects is larger than 233 BCM, which is greater than the surface water volume the country possesses. This indicates that the future water consumption by hydropower plants shall be revised in accordance with changes made in the final design of each planned projects. Nonetheless, this research provides scientific support for the argument that the production of hydroelectricity by reservoir regulated hydropower schemes, in countries like Ethiopia, is a water consumer. Thus, water allocation shall not ignore its demand.

A coupled surface water storage and subsurface water dynamics model in SWAT for characterizing hydroperiod of geographically isolated wetlands

Wetlands play an important role in watershed hydrology and biogeochemistry. A geographically isolated wetland (GIW) module for Soil and Water Assessment Tool (SWAT) was developed to couple surface water storage and subsurface water dynamics to characterize hydroperiod. The new GIW module includes the following features: (1) a flexible geometric formula to characterize wetland surface water area, volume, and depth; (2) a revised algorithm to account for evaporation from both water and soil surfaces in wetlands; (3) application of the Richards equation to couple surface water storage and subsurface water dynamics; (4) use of Darcy's law with an effective hydraulic conductivity parameter to simulate groundwater discharge. We tested the GIW module using observed daily water level data from four wetlands at two sites (including restored and natural wetlands with and without a low-permeability soil layer) in the Delmarva Peninsula, USA. The results show that the wetland module reasonably reproduced observed water levels for both restored and natural wetlands with and without a low-permeability soil layer. The module was also able to reasonably simulate saturated and unsaturated portions of the soil corresponding to wet and dry periods. The ability of the GIW module to describe inundation conditions for wetlands holds promise to enhance the understanding and quantification of hydrological and biogeochemical roles of GIWs in a watershed context.

Comparison of Surface Water Volume Estimation Methodologies That Couple Surface Reflectance Data and Digital Terrain Models

Uncertainty about global change requires alternatives to quantify the availability of water resources and their dynamics. A methodology based on different satellite imagery and surface elevation models to estimate surface water volumes would be useful to monitor flood events and reservoir storages. In this study, reservoirs with associated digital terrain models (DTM) and continuously monitored volumes were selected. The inundated extent was based on a supervised classification using surface reflectance in Landsat 5 images. To estimate associated water volumes, the DTMs were sampled at the perimeter of inundated areas and an inverse distance weighting interpolation was used to populate the water elevation inside the flooded polygons. The developed methodology (IDW) was compared against different published methodologies to estimate water volumes from digital elevation models, which assume either a flat water surface using the maximum elevation of inundated areas (Max), and a flat water surface using the median elevation of the perimeter of inundated areas (Median), or a tilted surface, where water elevations are based on an iterative focal maximum statistic with increasing window sizes (FwDET), and finally a tilted water surface obtained by replacing the focal maximum statistic from the FwDET methodology with a focal mean statistic (FwDET_mean). Volume estimates depend strongly on both water detection and the terrain model. The Max and the FwDET methodologies are highly affected by the water detection step, and the FwDET_mean methodology leads to lower volume estimates due to the iterative smoothing of elevations, which also tends to be computationally expensive for big areas. The Median and IDW methodologies outperform the rest of the methods, and IDW can be used for both reservoir and flood volume monitoring. Different sources of error can be observed, being systematic errors associated with the DTM acquisition time and the reported volumes, which for example fail to consider dynamic sedimentation processes taking place in reservoirs. Resolution effects account for a fraction of errors, being mainly caused by terrain curvature.

Quantifying the Degree of Water Resource Utilization Polarization: A Case Study of the Yellow River Basin

The overexploitation of water resources has a substantial influence on their sustainable utilization and the ecological environment in a river basin. Quantification of the development and utilization of water resources plays an important role in guiding the rational utilization of water resources. Based on this, this paper develops the concept of water resource utilization polarization (WRUP) in order to qualitatively analyze whether water resources are being overexploited in the process of utilization. An index model of WRUP was built to quantify the degree of water resources overexploitation. In addition, taking seven secondary basins of the Yellow River as examples, the available quantity, overdraft and polarization indexes of surface water and groundwater resources were calculated. The results show that there are 34.49×108 m3 of surface water available, which accounts for 56.21% of the total surface water volume. A total of 5.84×108 m3 of groundwater is available, which is 58.74% of the total groundwater resources. We also found that the water resources are heavily overexploited and that there is extensive polarization in the middle and lower reaches of the Yellow River. The highest polarization of water resources occurs from Lanzhou to Toudaoguai where the polarization index is 19.88 and from Longmen to Sanmenxia where it is 11.81. There is no polarization above Longyangxia or from Toudaoguai to Longmen. Overall, the polarization of water resources is 7.95 over the entire Yellow River area. These results provide a reference for the availability of water resources that can be used to determine the degree of overexploitation of the water resources in the Yellow River.

Mine Waters of the Eastern Donbass and Their Effect on the Chemistry of Groundwater and Surface Water in the Region

Regularities in the formation of mining water chemistry in Eastern Donbass were established and described for the 100-year period from the 1920s to 2010. The total of more than 1500 analyses were used. The changes in the chemistry were largest in the 1940s–1950s in the mines that had been recovered during World War II and after the mass abandonment of mines in the region (2002–2010). The size of groundwater resources acceptable for drinking water supply had decreased considerably; and the volumes of polluted surface water had increased abruptly. The export of dissolved substances by mining waters onto land surface reached its maximum (426 thousand t/year) in 2010. Four main lines of transformation of mine water chemistry were identified and their genesis was interpreted.

Diagnosing drought using the downstreamness concept: the effect of reservoir networks on drought evolution

ABSTRACTTo effectively manage hydrological drought, there is an urgent need to better understand and evaluate its human drivers. Using the “downstreamness” concept, we assess the role of a reservoir network in the emergence and evolution of droughts in a river basin in Brazil. In our case study, the downstreamness concept shows the effect of a network of reservoirs on the spatial distribution of stored surface water volumes over time. We demonstrate that, as a consequence of meteorological drought and recovery, the distribution of stored volumes became spatially skewed towards upstream locations, which affected the duration and magnitude of hydrological drought both upstream (where drought was alleviated) and downstream (where drought was aggravated). The downstreamness concept thus appears to be a useful entry point for spatiotemporally explicit assessments of hydrological drought and for determining the likelihood of progression from meteorological drought to a human-modified hydrological drought in a basin.

Optimization of groundwater artificial recharge systems using a genetic algorithm: a case study in Beijing, China

An optimization approach is used for the operation of groundwater artificial recharge systems in an alluvial fan in Beijing, China. The optimization model incorporates a transient groundwater flow model, which allows for simulation of the groundwater response to artificial recharge. The facilities’ operation with regard to recharge rates is formulated as a nonlinear programming problem to maximize the volume of surface water recharged into the aquifers under specific constraints. This optimization problem is solved by the parallel genetic algorithm (PGA) based on OpenMP, which could substantially reduce the computation time. To solve the PGA with constraints, the multiplicative penalty method is applied. In addition, the facilities’ locations are implicitly determined on the basis of the results of the recharge-rate optimizations. Two scenarios are optimized and the optimal results indicate that the amount of water recharged into the aquifers will increase without exceeding the upper limits of the groundwater levels. Optimal operation of this artificial recharge system can also contribute to the more effective recovery of the groundwater storage capacity.

Influence of recent climatic events on the surface water storage of the Tonle Sap Lake

Lakes and reservoirs have been identified as sentinels of climate change. Tonle Sap is the largest lake in both the Mekong Basin and Southeast Asia and because of the importance of its ecosystem, it is has been described as the “heart of the lower Mekong”. Its seasonal cycle depends on the annual flood pulse governed by the flow of the Mekong River. This study provides an impact analysis of recent climatic events from El Niño 1997/1998 to El Niño 2015/2016 on surface storage variations in the Tonle Sap watershed determined by combining remotely sensed observations, multispectral images and radar altimetry from 1993 to 2017. The Lake's surface water volume variations are highly correlated with rainy season rainfall in the whole Mekong River Basin (R = 0.84) at interannual time-scale. Extreme droughts and floods can be observed when precipitation deficit and excess is recorded in both the Tonle Sap watershed and the Mekong River Basin during moderate to very strong El Niño/La Niña events (R = −0.70) enhanced by the Pacific Decadal Oscillation (R = −0.68). Indian and Western North Pacific Monsoons were identified as having almost equal influence. Below normal vegetation activity was observed during the first semester of 2016 due to the extreme drought in 2015.

Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data

Abstract. Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-mission remotely sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break-up provokes an increase in the river's flows. Thus, this phenomenon causes intensive floods along the delta every year, with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume are analysed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995–2003), ENVISAT (2002–2010) and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9600 km2 (±200 km2) on average, representing approximately 70 % of the delta's total surface. Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights (R > 0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 m compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km3 during the whole study period, with a maximum of 14.4 km3 observed in 2006. The good agreement between the total surface water volume retrievals and in situ river discharges (R= 0.66) allows for validation of this innovative multi-mission approach and highlights the high potential to study the surface water extent dynamics.

UJI COBA APLIKASI PEMANENAN AIR HUJAN DAN SUMUR RESAPAN DI WILAYAH BOGOR, DEPOK DAN JAKARTA

Areas of Jakarta, Bogor, Tangerang and Bekasi (Greater Jakarta) is an area with high rainfall (2250 -2500 mm/year). The rain that falls in this region often cause flooding problems in the area of rice fields, settlements and even in downtown. Rain is a gift from God to be utilized to the maximum extent possible for everyday purposes. Rain Water Harvesting is an attempt to capture rainwater that falls on the roof. In this study, use of the roof area of about 300 -500 m2. Precipitation that falls on the roof is channeled and put into storage, by first filtering done to reduce the dirt. The volume of rain water storage for each location is 10 m3, medium intensity rain (15-20 mm/h), sufficient to meet the storage within a few hours. Rain Water Reservoir are equipped with water pump which has a capacity of 25 liters/minute, the water can be used for flushing toilets and spraying crops. If Rain Water Reservoir is full, water overflows into the Artificial recharge well. The results of analysis with Kostiokov calculation method used to calculate the infiltration rate of Artificial recharge well and calculate the cumulative volume of infiltration at the Artificial recharge well. Results of tests conducted are as follows: a). In Depok, the infiltration rate of Artificial Recharge Well is about 12 mm/minute and was relatively stable at 140 minute (2 mm/minute). It also has the ability to recharge 450 liters of water in 140 minutes. b). In South Jakarta, the infiltration rate of Artificial Recharge Well is about 11 mm/minute and was relatively stable at 160 minutes (2.5 mm/minute). Artificial Recharge Well has the ability to recharge 480 liters of water in 160 minutes. c). In Bantarjati, Bogor, Artificial Recharge Well have the highest capacity, namely 45 mm/minute and was relatively stable at 260 minutes (2.5 mm/minute). Artificial Recharge Well has the ability to recharge 1000 liters of water in 150 minutes. Rain Water Harvesting Development Efforts and Artificial Recharge Well very useful to overcome inundation in residential areas, especially during heavy rain, because it can reduce the volume of surface water into the channel simultaneously. Keywords : Rain Water Harvesting, Infiltration, Artificial Recharge.

Estimating restorable wetland water storage at landscape scales.

Globally, hydrologic modifications such as ditching and subsurface drainage have significantly reduced wetland water storage capacity (i.e., volume of surface water a wetland can retain) and consequent wetland functions. While wetland area has been well documented across many landscapes and used to guide restoration efforts, few studies have directly quantified the associated wetland storage capacity. Here, we present a novel raster-based approach to quantify both contemporary and potential (i.e., restorable) storage capacities of individual depressional basins across landscapes. We demonstrate the utility of this method by applying it to the Delmarva Peninsula, a region punctuated by both depressional wetlands and drainage ditches. Across the entire peninsula, we estimated that restoration (i.e., plugging ditches) could increase storage capacity by 80%. Focusing on an individual watershed, we found that over 59% of restorable storage capacity occurs within 20 m of the drainage network, and that 93% occurs within 1 m elevation of the drainage network. Our demonstration highlights widespread ditching in this landscape, spatial patterns of both contemporary and potential storage capacities, and clear opportunities for hydrologic restoration. In Delmarva and more broadly, our novel approach can inform targeted landscape-scale conservation and restoration efforts to optimize hydrologically mediated wetland functions.

Influence of instantaneous and time‐averaged groundwater flows induced by waves on the fate of contaminants in a beach aquifer

AbstractWave‐induced water exchange and groundwater flows in beach aquifers impact the fate of contaminants including nutrients, fecal bacteria, and nonaqueous phase liquids (NAPLs). Waves induce high‐frequency fluxes in shallow beach sediments. In addition, the phase‐averaged effect of waves (wave setup) drives deeper flow recirculations through a beach aquifer. Field data of shallow instantaneous and time‐averaged vertical head gradients (fluxes) are first compared with deeper time‐averaged fluxes over a period of varying wave conditions. The time‐averaged fluxes are equivalent to that which would be simulated assuming a phase‐averaged water surface (i.e., wave setup). Based on this comparison, the need to simulate phase‐resolved wave motion versus the simplified phase‐averaged water surface in predicting contaminant fate is evaluated. While high‐frequency fluxes cause large surface water volumes to filter through beach sediments, the exchanging water has a short residence time (<1–70 s). The time‐averaged flow behavior captures exchanging water with longer residence time (hours to months) and deeper flow paths. Therefore, consideration of the time‐averaged behavior may be sufficient for evaluating dissolved reactive constituents. In contrast, calculations indicate that instantaneous fluxes may need to be considered in evaluating colloidal contaminants (e.g., particulate organic matter and fecal bacteria) as sediment interactions affect their transport and residence time. Finally, multiphase simulations illustrate the differential effect of considering instantaneous versus time‐averaged fluxes on the downward migration of NAPL in beach sediments. This study provides an important foundation for future field and modeling efforts focused on understanding and predicting contaminant transport in wave‐influenced beaches.

Underground water resources in Kazakhstan

The assessment of natural resources and the ecological demand for underground water in Kazakhstan is based on a water-balance equation which considers underground lateral flow, hydrogeoecological regions and river basins. We propose a methodology to estimate the underground water resource for this region. The flow of water in all the rivers of Kazakhstan is estimated at 102.3 km3/year, of which 57.6 km3/year originates in the territory of the country, and 44.7 km3/year in the adjacent countries. With potential increase of the underground water usage up to 15.5 km3/year, the surface water volume could be decreased to 5 km3/year. Optimization of water resource use should be based on the introduction of the water-efficient process of reinjecting and recycling the water supply in all branches of industry, and a reduction in losses during distribution.

Ecosystem functions and services of cloud afromontane forests in Ethiopia

Using meta data on crop output, crop output together with productivity of animal husbandry, surface water volume, ground water volume and cover of cloud wet afromontane forests in selected four regions which are major food producers in Ethiopia the functions and the services of the forests were modelled. Forest cover significantly and positively explained agricultural productivity, surface and ground water volume in Ethiopia. In similar regression modeling it was determined that food productivity across regions was result of the volume of surface water and ground water. This clearly indicates unwarranted destructive alteration of the forest cover in the country would have unprecedented negative effects thereby exasperating natural disasters which ultimately will cause a negative shock to the overall economy. Furthermore increasing forest cover through the planting of trees and others would have significant positive effect on the economy which enhances the wellbeing of a significant portion of the population in the country. Key Words: Ecosystem Functions, Ecosystem Services, Ethiopia

Cleanup and valuation of waters of the aquifer of M’zab Valley (Algeria)

Abstract The M’zab valley is a hyper arid region of average rainfall not exceeding 100 mm per year. However, the rare floods that occur in M’zab River drain large volumes of surface water. Thanks to the genius of the local population, traditional dams were made for artificial recharge of groundwater. Grace of traditional wells drilled in the valley, farmers irrigate their palm groves and gardens. However, since more than half a century, the contribution of deep drilling for the exploitation of the aquifer of the Continental Intercalary posed environmental problems. On the basis of investigations and surveys of the local population during the years 2010, 2011, 2012 and 2013, it appears that these modern techniques in water catchment caused harmful consequences to the region like the rising of water consumption, pollution of groundwater and soil salinity. Solutions and recommendations are outlined in this article.

Long-term (11 years) study of water balance, flushing times and water chemistry of a coastal wetland undergoing restoration, Everglades, Florida, USA

Upstream water diversions have significantly reduced freshwater flow to coastal wetlands of the Everglades. The purpose of this research was to investigate the water balance, flushing time, and water chemistry of Taylor Slough; one of the main natural waterways of the coastal Everglades, during its early stages of restoration. Both the water balance and flushing times were calculated on a monthly basis from 2001 to 2011. Surface water chemistry was analyzed using 3-day composite samples collected every 18h. Current restoration efforts have been able to increase surface water inputs to southern Taylor Slough, but rainfall was still the dominant water input. Flushing times varied between 3 and 78days, with the highest values occurring in December and the lowest in May. Flushing times were negatively correlated with evapotranspiration (ET), but were longer when surface water volume exceeded ET and shorter when ET exceeded water volume. Surface water concentrations of calcium and chloride along with total nitrogen and total phosphorus were negatively correlated with flushing times. The results herein suggest that in coastal wetlands with low quantities of surface water inputs, ET and surface water volume influenced by rainfall are the most dominant factors influencing flushing times and water chemistry. Increased surface water inflows with additional restoration efforts would be expected to increase surface water volumes into southern Taylor Slough, thereby increasing flushing times and decreasing ion and nutrient concentrations.