Status Of Surface Waters Research Articles

What Are the Benefits of the Water Framework Directive? Lessons Learned for Policy Design from Preference Revelation

The Water Framework Directive (WFD) seeks to achieve good ecological status of surface waters across the European Union by 2027. The WFD guidelines explicitly recognize the economics of water management by providing exceptions to water areas with disproportionately high restoration costs. This calls indirectly for estimations of benefits lost due to non-attainment. We employ a hedonic property pricing approach on waterfront recreational properties to estimate the welfare impacts of attaining the good ecological status described by the WFD. The empirical challenge is that the quality measure proposed by the WFD specifically denotes ecological quality, whereas economically measurable water quality values are heavily dependent on recreation impacts. Intuitively, the choice of water quality measure should have an effect on estimating the value of water quality. Our data provide a unique chance to compare three alternative indicators of water quality: (1) a usability-based index, (2) subjectively reported measure and (3) the ecological status determined by the WFD. We find that an improvement in water quality is associated with a statistically significant, non-linear change in recreational property values. We show how the ecological status compares with the other two indicators, and discuss the justifiability of using revealed preference methods when the valued good is defined purely on the basis of ecological criteria.

Open, Sharable, and Extensible Data Management for the Korea National Aquatic Ecological Monitoring and Assessment Program: A RESTful API-Based Approach

Implemented by a national law, the National Aquatic Ecological Monitoring Program (NAEMP) has been assessing the ecological health status of surface waters, focusing on streams and rivers, in Korea since 2007. The program involves ecological monitoring of multiple aquatic biota such as benthic diatoms, macroinvertebrates, fish, and plants as well as water quality and habitat parameters. Taking advantage of the national scale of long-term aquatic ecological monitoring and the standardization of protocols and methods, the datasets in NAEMP provide many opportunities for various advanced comparative and synthetic studies, policy-making, and ecological management. In order to realize these potentials and opportunities, we have developed a RESTful API-based data management system called OSAEM (the Open, Sharable and Extensible Data Management System for Aquatic Ecological Monitoring), which is designed to be open, sharable, and extensible. In this paper, we introduce the RESTful API-based data management approach, present the RESTful API for the OSAEM system, and discuss its applicability. An OSAEM prototype system is currently available on a commercial cloud service (Amazon EC2) but the system remains under active development.

Approaches for integrated assessment of ecological and eutrophication status of surface waters in Nordic Countries.

We review approaches and tools currently used in Nordic countries (Denmark, Finland, Norway and Sweden) for integrated assessment of 'ecological status' sensu the EU Water Framework Directive as well as assessment of 'eutrophication status' in coastal and marine waters. Integration principles for combining indicators within biological quality elements (BQEs) and combining BQEs into a final-integrated assessment are discussed. Specific focus has been put on combining different types of information into indices, since several methods are currently employed. As a consequence of the variety of methods used, comparisons across both BQEs and water categories (river, lakes and coastal waters) can be difficult. Based on our analyses, we conclude that some principles and methods for integration can be critical and that a harmonised approach should be developed. Further, we conclude that the integration principles applied within BQEs are critical and in need of harmonisation if we want a better understanding of potential transition in ecological status between surface water types, e.g. when riverine water enters a downstream lake or coastal water body.

Estimating Soil Moisture with Landsat Data and Its Application in Extracting the Spatial Distribution of Winter Flooded Paddies

Dynamic monitoring of the spatial pattern of winter continuously flooded paddies (WFP) at regional scales is a challenging but highly necessary process in analyzing trace greenhouse gas emissions, water resource management, and food security. The present study was carried out to demonstrate the feasibility of extracting the spatial distribution of WFP through time series imagery of volumetric surface soil moisture content (θv) at the field scale (30 m). A trade-off approach based on the synergistic use of tasseled cap transformation wetness and temperature vegetation dryness index was utilized to obtain paddy θv. The results showed that the modeled θv was in good agreement with in situ measurements. The overall correlation coefficient (R) was 0.78, with root-mean-square ranging from 1.96% to 9.96% in terms of different vegetation cover and surface water status. The lowest error of θv estimates was found to be restricted at the flooded paddy surface with moderate or high fractional vegetation cover. The flooded paddy was then successfully identified using the θv image with saturated moisture content thresholding, with an overall accuracy of 83.33%. This indicated that the derived geospatial dataset of WFP could be reliably applied to fill gaps in census statistics.

Hydrochemical and isotopic characters of surface water in agricultural oases of the Tianshan Mountains, Northwest China

ABSTRACTFor evaluating the status of surface water in agricultural oases of the Tianshan Mountains and discussing the influences of human activities and geographical factors on hydrochemical process, we conducted hydrochemical investigations of surface water in two major agricultural oases: Manas and Yili. The δ2H and δ18O of surface water in Manas Oasis ranged from −75.4‰ to − 46.2‰ and −11.6‰ to − 5.5‰, respectively, and from −86.4‰ to − 71.8‰ and −12.5‰ to − 10.7‰ in Yili Oasis. Because rivers are mainly supplied by meltwater from ice and snow, the deuterium excess parameter is mostly positive in the oasis surface waters supplied by these rivers. Ca2+-Mg2+- is the major hydrochemical facies type in Yili and Manas oases. Surface waters of both regions are slightly saturated with carbonate minerals and undersaturated with respect to evaporite minerals, suggesting that the minerals present in the water are mainly produced by calcite and dolomite weathering. Total dissolved solids (TDS) in Manas Oasis are higher than those in Yili Oasis. The δ2H and δ18O of surface water samples in Manas Oasis are isotopically enriched, which indicates that the evaporation effect on Manas is stronger than on Yili. The relatively high salinity in Manas is also associated with local contamination by soil leaching. Agricultural activities are important to the quality of surface water. If such activity is not controlled, water salinization will be increased. Clarification of the hydrological status of these oases and their factors will be used for water management and protection of agricultural oases.

EVALUATION OF HARGREAVES BASED ON REMOTE SENSING METHOD TO ESTIMATE POTENTIAL CROP EVAPOTRANSPIRATION

In arid and semi-arid regions, agricultural water consumption information is very important to managing and developing water resources. Potential crop evapotranspiration (ETc) is the major parameter in agricultural water resources management. Remote sensing techniques were involved in this work to evaluate Hargreaves method for estimating ETc depending on satellite data. The difference between air temperature (Tair) and Land Surface Temperature (LST) varies particularly by surface water status. Normalized Difference Vegetation Index (NDVI) was extracted from NOAA/AVHRR and landsat8 satellite data to calculate emissivity as an intermediate step for producing LST. Linear relation between Tair and LST was established and R 2 was 0.93. Reference evapotranspiration (ETo) was estimated using agro-meteorological data through FAO-Penman-Monteith (FPM) which used as standard method and Hargreaves (Har) method. To calibrate ETo-Har, the ETo-FPM was used under the same conditions. Landsat8 data acquired on 13 th of Aug. and 08 th of Aug. 2014 and were used to calculate Crop coefficient (Kc) based on satellite data (Kc-Sat). LST was used to predict Tair ( o C) in Aug. 2014. ETo estimated using Har method and was used with Kc-Sat to estimate ETc-Har. ETo-FPM combined with Kc-Sat to estimate ETc-FPM. ETc-FPM used to evaluate ETc-Har. The relation between ETc- FPM and ETc-Har was very strong where R 2 as high as 0.99.

Estimating cultural benefits from surface water status improvements in freshwater wetland ecosystems

Freshwater wetlands provide crucial ecosystem services, though are subject to anthropogenic/natural stressors that provoke negative impacts on these ecosystems, services and values. The European Union Water Framework Directive aims to achieve good status of surface waters by 2015, through implementation of Catchment Management Plans. Implementation of Catchment Management Plans is costly, though associated benefits from improvements in surface water status are less well known. This paper establishes a functional relationship between surface water status and cultural ecosystem service values of freshwater systems. Hence, we develop a bio-economic valuation approach in which we relate ecological status and chemical status of surface waters (based on local physio-chemical and benthic macro-invertebrates survey data) to willingness-to-pay (using benefit-function transfer). Results for the Pateira de Fermentelos freshwater wetland (Portugal) show that the current status of surface waters is good from a chemical though only moderate from an ecological perspective. The current cultural ecosystem service value of the wetland is estimated at 1.54 m€/yr— increasing to 2.02 m€/yr in case good status of surface waters is obtained. Taking into account ecosystem services and values in decision making is essential to avoid costs from externalities and capture benefits from spill-overs — leading to more equitable, effective and efficient water resources management.

Adaptation through Watershed Management in the Changing Climate

<p>Civilization has been experiencing frequent changes in the climate due to global warming.</p> <div> <p>The developing nations are worst affected as they are largely dependent on the local precipitation and soil moisture for their livelihood generations. The changing climate with extended summer, change in the rainfall pattern (intensity and duration) and variations of onset and departure of seasons are directly impacting the cultivation, status of natural vegetation, surface and sub-surface water, and other natural resources in a watershed area. Among the various efforts, watershed development approach, in which intervention is more site-specific in nature and can address the local requirements, is found to be more effective at micro levels. The vulnerability of climatic changes is mainly due to water stress, degradation of natural vegetations, degradation in the health and hygiene conditions, and poor information communication technology. The present article highlights these issues, impact of watershed development project in the Himalayan region and identifying the adaptation mechanism through watershed programs. A site specific action, research methods including primary and secondary data collections, GIS, remote sensing and statistical techniques were used. The study on the Jusho Bakro micro-watershed treated by TERI under the program DROP has been found to be effective in drawing possible adapting mechanism to withstand the changing climate and its severity on the natural resources and the livelihood of the community.</p> </div> <p> </p>

Assessment of metallic pollution status of surface water and aquatic macrophytes of earthen dams in Ilorin, north-central of Nigeria as indicators of environmental health

The functional quality of an aquatic ecosystem is a reflection of the health of the environment. Therefore, the present study evaluates the trace metal contamination (Pb, Cd, Ni and Mn) of water and aquatic macrophytes in Asa, Agba, Unilorin and Sobi (Moro) earthen dams, north-central Nigeria to evaluate the level of anthropogenic impact on the immediate environment. The concentrations of trace metals in samples of water and available macrophytes from the earthen dams were determined by Atomic Absorption Spectrophotometry. Trace metal contamination of surface water in the earthen dams was assessed using metal index (MPI) and metal pollution index (HPI). The biological accumulation factor of trace metals in the aquatic macrophytes was extrapolated from trace metal concentrations in the water and macrophyte samples. The results of the MPI revealed gross metal contamination of the surface water by Pb and Cd (>6.0 for both metals) in the four earthen dams; while Agba and Sobi dams were slightly contaminated by Ni (MPIs=1.43 and 1.14 respectively). All the earthen dams were considered safe from Mn contamination (MPI<1.0). Considering the HPI, the four earthen dams fall within the critical pollution threshold for trace metals (HPI>100), but Asa dam (HPI=2682.4) was the most contaminated. The biological accumulation factor of Mn in the macrophytes indicated Ceratophyllum demersum, Pycreus lanceolatus and Pistia stratiotes as moderate accumulators of Mn, and can be used as bioindicators in monitoring Mn pollution of aquatic ecosystem. The obtained results in this study showed that the earthen dams are polluted by Pb, Cd and Ni which pose human health risks to the inhabitants through drinking water.

Continuous Bayesian networks for probabilistic environmental risk mapping

Bayesian networks (BNs) are being increasingly applied to environmental research. Nonetheless, most of the literature related to environmental sciences use discrete or discretized data, which entails a loss of information. We propose a novel methodology based on continuous BNs to predict the probability that surface waters do not meet the standards, in relation to nitrate concentration, established by the European Water Framework Directive. In order to achieve our purpose, a Tree Augmented Naive Bayes (TAN), was developed and applied to estimate and map the risk of failing to meet the European standards established. The TAN models were tested by means of the k-fold cross validation method. The results revealed that the TAN model performed proper risk maps and suggested that poor water quality is highly probable in watersheds dominated by irrigated herbaceous crops. On the contrary, “good surface water status” is more likely to occur in areas where forest is notably present.

Initial Characterization and Water Quality Assessment of Stream Landscapes in Northern Mongolia

A comprehensive monitoring project (2006–2013) provided data on hydrology, hydromorphology, climatology, water physico-chemistry, sedimentology, macroinvertebrate community and fish diversity in the Kharaa River basin in northern Mongolia, thus enabling, for the first time, a detailed characterization of the stream landscapes. Surface waters were categorized into separate “water bodies” according to their identifiable abiotic and biocoenotic features, subsequently creating the smallest management sub-units within the river basin. Following the approach of the European Water Framework Directive (EC-WFD), in order to obtain a good ecological status (GES), four clearly identifiable water bodies in the Kharaa River main channel and seven water bodies consisting of the basin’s tributaries were delineated. The type-specific undisturbed reference state of various aquatic ecosystems was identified in the assessment and used to set standards for restoration goals. With regards to water quality and quantity, the upper reaches of the Kharaa River basin in the Khentii Mountains were classified as having a “good” ecological and chemical status. Compared with these natural reference conditions in the upper reaches, the initial risk assessment identified several “hot spot” regions with impacted water bodies in the middle and lower basin. Subsequently, the affected water bodies are at risk of not obtaining a level of good ecological and/or chemical status for surface waters. Finally, a matrix of cause-response relationships and stressor complexes has been developed and is presented here. The applicability of management approaches is discussed to better foster the development of a sustainable river basin management plan. The application of natural references states offers a sound scientific base to assess the impact of anthropogenic activities across the Kharaa River basin.

Application of remote sensing for the optimization of in-situ sampling for monitoring of phytoplankton abundance in a large lake

Directives and legislations worldwide aim at representatively and continuously monitoring the ecological status of surface waters. In many countries, chlorophyll-a concentrations (CHL) are used as an indicator of phytoplankton abundance and the trophic level of lakes or reservoirs. In-situ measurements of water quality parameters, however, are time-consuming, costly and of unknown but naturally limited spatial representativeness. In addition, the variety of the involved lab and field measurement methods and instruments complicates comparability and reproducibility.Taking Lake Geneva as an example, 1234 satellite images from the MERIS sensor on the Envisat satellite from 2002 to 2012 are used to quantify the spatial and temporal variations of CHL concentrations. Based on histograms of spring, summer and autumn CHL estimates, the spatial representativeness of two existing in-situ measurement locations is analysed. Appropriate sampling frequencies to capture CHL peaks are examined by means of statistical resampling. The approaches proposed allow determining optimal in-situ sampling locations and frequencies. Their generic nature allows for adaptation to other lakes, especially to establish new survey programmes where no previous records are available.

Investigations on sediment toxicity of German rivers applying a standardized bioassay battery.

River sediments may contain a huge variety of environmental contaminants and play a key role in the ecological status of aquatic ecosystems. Contaminants adsorbed to sediments and suspended solids may contribute directly or after remobilization to an adverse ecological and chemical status of surface water. In this subproject of the joint research project DanTox, acetonic Soxhlet extracts from three German river sediments from the River Rhine (Altrip and Ehrenbreitstein with moderate contamination) and River Elbe (Veringkanal Hamburg heavily contaminated) were prepared and redissolved in dimethyl sulfoxide (DMSO). These extracts were analyzed with a standard bioassay battery with organisms from different trophic levels (bacteria, algae, Daphnia, fish) as well as in the Ames test and the umuC test for bacterial mutagenicity and genotoxicity according to the respective OECD and ISO guidelines. In total, 0.01% (standard) up to 0.25% (only fish embryo test) of the DMSO sediment extract was dosed to the test systems resulting in maximum sediment equivalent concentrations (SEQ) of 2 up to 50 g l(-1). The sediment of Veringkanal near Hamburg harbor was significantly more toxic in most tests compared to the sediment extracts from Altrip and Ehrenbreitstein from the River Rhine. The most toxic effect found for Veringkanal was in the algae test with an ErC50 (72 h) of 0.00226 g l(-1) SEQ. Ehrenbreitstein and Altrip samples were about factor 1,000 less toxic. In the Daphnia, Lemna, and acute fish toxicity tests, no toxicity at all was found at 2 g l(-1) SEQ. corresponding to 0.01% DMSO. Only when increasing the DMSO concentration the fish embryo test showed a 22-fold higher toxicity for Veringkanal than for Ehrenbreitstein and Altrip samples, while the toxicity difference was less evident for the Daphnia test due to the overlaying solvent toxicity above 0.05% dimethyl sulfoxide (DMSO). The higher toxicities observed with the Veringkanal sample are supported by the PAH and PCB concentrations analyzed in the sediments. The sediment extracts of Altrip and Veringkanal were mutagenic in the Ames tester strain TA98 with metabolic activation (S9-mix). The findings allow a better ecotoxicological characterization of the sediments extensively analyzed in all subprojects of the DanTox project (e.g., Garcia-Kaeufer et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3894-4 , 2014; Schiwy et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3185-0 , 2014; Hollert and Keiter 2015). In the absence of agreed limit values for sediment extracts in standard tests, further data with unpolluted reference sediments are required for a quantitative risk assessment of the investigated polluted sediments.

Assessing the impacts of climate change on water quantity and quality modelling in small Slovenian Mediterranean catchment - lesson for policy and decision makers

The study aims to address the long-term impacts of six different downscaled Regional Climate Models (RCM) climate models on the quantity (river flow) and quality (sediment load, total nitrogen load and total phosphorus load) state of surface waters in the river Reka catchment, in the northern Mediterranean. Mediterranean areas are – due to high population density, favourable natural conditions for agriculture, limited water resources, diverse ecosystems biodiversity and expected climate change impacts – a global hotspot in climate research. Additionally, the study area lies on the border with the alpine climate zone, with a strong orographic effect on weather patterns. The location, and a wide range of studied parameters, provides an interesting insight into how various emerging climate change models may impact the status of surface waters and procedures for the governance of water resources. The study contributes to the knowledge and understanding of the climate change impact on the local catchment level, using the ensemble of the RCMs. It opens discussion about the impact of RCM selection on modelling climate changes with catchment models like Soil and Water Assessment Tool. This article also questions the usability of the results for the policy and decision makers in relation to the implementation of the results into short or long-term water strategies or water/river management plans. Copyright © 2015 John Wiley & Sons, Ltd.

Air pollutant contamination and acidification of surface waters in the North York Moors, UK: Multi-proxy evidence from the sediments of a moorland pool

Despite the extensive geographical range of palaeolimnological studies designed to assess the extent of surface water acidification in the United Kingdom during the 1980s, little attention was paid to the status of surface waters in the North York Moors (NYM). In this paper, we present sediment core data from a moorland pool in the NYM that provide a record of air pollution contamination and surface water acidification. The 41-cm-long core was divided into three lithostratigraphic units. The lower two comprise peaty soils and peats, respectively, that date to between approximately 8080 and 6740 cal. BP. The uppermost unit comprises peaty lake muds dating from between approximately ad 1790 and the present day (ad 2006). The lower two units contain pollen dominated by forest taxa, whereas the uppermost unit contains pollen indicative of open landscape conditions similar to those of the present. Heavy metal, spheroidal carbonaceous particle, mineral magnetics and stable isotope analysis of the upper sediments show clear evidence of contamination by air pollutants derived from fossil-fuel combustion over the last c. 150 years, and diatom analysis indicates that the naturally acidic pool became more acidic during the 20th century. We conclude that the exceptionally acidic surface waters of the pool at present (pH = c. 4.1) are the result of a long history of air pollution and not because of naturally acidic local conditions. We argue that the highly acidic surface waters elsewhere in the NYM are similarly acidified and that the lack of evidence of significant recovery from acidification, despite major reductions in the emissions of acidic gases that have taken place over the last c. 30 years, indicates the continuing influence of pollutant sulphur stored in catchment peats, a legacy of over 150 years of acid deposition.

Construction of a typology system for rivers in Chile based on the European Water Framework Directive (WFD)

To assess the current status of surface waters, it is necessary, as a first step, to have a system that includes a set of criteria for classifying and describing each existing surface water body. In this article, a new river typology system for Chile based on the Water Framework Directive of the European Union is shown. This system was created following a top down and a priori approach and was based on an accurate review of scientific literature, interviews and workshops with experts in Chilean aquatic ecosystems. The system consisted of five ecoregions (large areas with homogenous hydrological and climatic conditions) and a set of abiotic criteria with their classes. It was assumed that each abiotic criterion was a control factor for freshwater ecosystems. It is expected that this system will organise knowledge about the biocenosis distribution of the Chilean freshwater ecosystem and also provide an operative tool for water quality monitoring based on biological indicators.

English

Study on arsenic pollution was conducted in Onitsha town in Anambra State, Nigeria to examine the pollution status of surface and subsurface water. Arsenic concentration in surface water within Onitsha metropolis ranged from 0.2001 mg/L (River Niger upstream) to 1.5883 mg/L (River Niger central drainage surface), while concentration in boreholes lies within the range of 0.0000 mg/L (22.2% of boreholes) and 1.2507 mg/L (creek road), respectively. Arsenic concentration in sampled water from river sources is above the WHO standard (0.01 mg/ L) while 87.8% of Arsenic concentration in boreholes adjacent and closest to these rivers and creek is also above the world Health Organization standard (WHO, 2011) of 0.01 mg/L. it is discovered that pollution of surface water is greater than that of the groundwater sources. Major sources of arsenic in Onitsha are refuse dumps, effluent from industries and sewage amongst other sources. Arsenic is known to be the most poisonous metal in existence on earth’s surface, its production should be carefully monitored and effluents treated before discharge into the environment. Key words: Arsenic, water, health.

Assessment of sediment ecotoxicological status as a complementary tool for the evaluation of surface water quality: the Ebro river basin case study

According to the European Water Framework Directive (WFD), assessment of surface water status is based on ecological and chemical status that is not always in coherence. In these situations, ecotoxicity tests could help to obtain a better characterization of the ecosystems. The general aim of this work is to design a methodology to study the ecotoxicological status of freshwater systems. This could be useful and complementary to ecological status, for a better ecological characterization of freshwater systems. For this purpose, sediments from thirteen sampling sites within the Ebro river watershed (NE Spain) were collected for ecotoxicity characterization. The ecotoxicity of pore water has been evaluated employing the test organisms Vibrio fischeri, Pseudokirschneriella subcapitata and Daphnia magna, while whole sediment ecotoxicity was evaluated using Vibrio fischeri, Daphnia magna, Nitzschia palea and Chironomus riparius. An analysis of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) was performed to evaluate the sediment toxicity associated to bioavailable metals. Moreover, data about priority pollutants defined by the WFD in water, sediment and fish as well as data of surface water status of each sampling point were provided by the Monitoring and Control Program of the Ebro Water bodies. In general terms, whole sediment bioassays have shown more toxicity than pore water tests. Among the different organisms used, P. subcapitata and C. riparius were the most sensitive in pore water and whole sediment, respectively. Our evaluation of the ecotoxicological status showed high coincidences with the ecological status, established according to the WFD, especially when ecosystem disruption due to numerous stressors (presence of metals and organic pollution) was observed. These results allow us to confirm that, when chemical stressors affect the ecosystem functioning negatively, an ecotoxicological approach, provided by suitable bioassays in pore water and whole sediment, could detect these changes with accurate sensitivity.

Determination of ecological status and ecological preferences of phytoplankton using multivariate approach in a Mediterranean reservoir

The European Union Water Framework Directive includes phytoplankton as one of the mandatory five biological indicators to be used to assess the ecological status of surface waters. The objective of the study was determination of ecological status and ecological preferences of phytoplankton from April 2012 to June 2013, using multivariate approach in Alleben Reservoir in the southeast Turkey. The reservoir showed a warm monomictic stratification pattern (stratification in April–October 2012 vs. mixing in November 2012–March 2013). The reservoir was meso-eutrophic according to phosphorus, chlorophyll a, and transparence values. Phytoplankton biovolume reached remarkable peaks in autumn and spring. Phytoplankton species belong to functional groups of A, D, E, J, LO, LM, MP, P, and Y as descriptor. Phytoplankton trophic index (PTI) and assemblage index (Q) indicated the overall medium ecological status of Alleben Reservoir. PTI and Q indices may be appropriate phytoplankton metrics to assess the ecological status of the reservoir. Changes in environmental gradients significantly influenced the ecological preferences of species and phytoplankton abundance in the reservoir. Canonical correspondence analysis (CCA) confirmed that phytoplankton species were sensitive to environmental variability, with the first two axes of CCA able to explain 92.8% of the total variation and 37.1% of the cumulative percentage variance in the phytoplankton assemblage structure. Most effective explanatory factors (e.g., salinity, conductivity, pH, and temperature) played significant role (P = 0.002) in the seasonality of species.

Remotely sensing the ecological influences of ditches in Zoige Peatland, eastern Tibetan Plateau

Zoige Peatland in the eastern Tibetan Plateau, the largest alpine peatland in China, was widely ditched in 1970s for pasture expansion. The ditching is believed to have caused peatland degradation, but there is still no widespread agreement on this due to the absence of essential regional and temporal information about ditch drainage. Therefore, this study used both remote-sensing observations and field surveys to examine the ecological influences of ditching for this alpine peatland. In the study, ditch distribution was interpreted with remote-sensing imagery and the ecological responses were investigated with temporal observation by Moderate Resolution Imaging Spectroradiometer (MODIS) and field surveys. The results showed that there were ~1200 km ditches interpreted, mainly in three spatial patterns depending on hydro-geomorphologies. The MODIS enhanced vegetation index (EVI) was more sensitive to peatland surface water depth (R2 = 0.678, P < 0.001) than the normalized difference water index (NDWI) (R2 = 0.583, P < 0.001), because the latter would become saturated at a certain surface water depth (~50 cm in Zoige). The temporal MODIS imagery reflected the ecological responses of ditched peatland to drainage in terms of vegetation density and water conditions. This study indicated that ditching depressed the surface water depth of the Zoige Peatland in summer, but not to the extent of completely transforming peatland into steppe due to the recharging of local beneficial hydro-geomorphologies. The MODIS indices investigated in the study could be used to monitor the annual regional status of vegetation cover and surface water for Zoige peatland.