Hydrological Indicators Research Articles

Multivariate Analyses of Selected Hydro-bacterial Variables along the Longitudinal Gradient of Orani River, Philippines

There is paucity of environmental data for Orani river systems in Bataan (Philippines) despite its regional economic and ecological significance. The present study conducted multivariate analyses of various water quality parameters and selected bacterial communities to evaluate the river’s health integrity. River data exhibited spatial and seasonal variation, with observed significantly distinct heterotrophic and Gram-negative bacterial counts in the midstream and downstream against upstream samples. Fecal coliform concentrations were statistically different in the sequence: upstream < downstream < midstream. Multivariate Principal Component Analysis identified the most important variables affecting the variability in bacterial concentrations among the sampling groups (81.64% variation). Cluster analysis also revealed the associations and similarities of sampling groups based on abundance of bacterial loadings. Further, water quality indices were classified within “marginal” class (54.77 for wet season; 57.67 for dry season). The hydrological index estimated a score of 47.97 for wet season that described as “suitable with high restriction” class (30<(HI)c<55), and 62.24 for dry season in the “suitable with medium restriction” class (55<(HI)c<75).

Hydrological Extremes and Responses to Climate Change in the Kelantan River Basin, Malaysia, Based on the CMIP6 HighResMIP Experiments

This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were computed to assess future extreme flows in the Kelantan River Basin (KRB), Malaysia, which is particularly vulnerable to flooding. Results show that the annual precipitation, streamflow, maximum and minimum temperatures are projected to increase by 6.9%, 9.9%, 0.8 °C and 0.9 °C, respectively, by the 2021–2050 period relative to the 1985–2014 baseline. Monthly precipitation and streamflow are projected to increase especially for the Southwest Monsoon (June–September) and the early phase of the Northeast Monsoon (December) periods. The magnitudes of the 1-, 3-, 7-, 30- and 90-day minima flows are projected to increase by 7.2% to 8.2% and the maxima flows by 10.4% to 28.4%, respectively. Lastly, changes in future hydro-climatic extremes are frequently quite different between the high-resolution and low-resolution models, e.g., the high-resolution models projected an increase of 11.8% in mean monthly flow in November-December-January compared to 3.2% for the low-resolution models.

PARASITOCENOSES OF FISH IN RIVERS AND RESERVOIRS OF THE RYAZAN REGION

The wide distribution of trematodes and other helminths with a complex biological cycle in the reservoirs of the Ryazan Region indicates an increase in the level of their eutrophication. We performed a complete helminthological study of the ide (25 copies), roach (21 copies), and perch (29 copies) according to K.I. Skryabin. Taking into account complex hydrological indicators (species composition of higher plants, microphytes, fauna of hydrobionts and their parasites), the Pra River is a dystrophic water body, the Pronya River is an eutrophic water body, and the Novomichurinsk Reservoir is a hypertrophic water body. Parasites of Pra River were represented by nine species, the Pronya River by four species, and the Novomichurinsky Reservoir by six species. Trematodes dominate in all reservoirs of the Ryazan Region. We found an endemic focus of opisthorchiasis in the Pra River where the infection of the ide with metacercarias Opisthorchis felineus reaches 38–50% with an invasion intensity of up to 70 specimens. A number of species of trematodes (Ichthyocotylurus spp., Paracoenogonimus ovatus, Diplostomum spp., Posthodiplostomum spp., Tylodelphys clavata) and cestodes (Ligula intestinalis) should be considered as indicators for assessing an increase in concentration of dissolved biogenic substances in the water bodies. There is a direct correlation between the infection of fish with the above species of trematodes and cestodes (tapeworms) being indicators of the invasion intensity and the degree of eutrophication of the reservoirs.

Identification of Extreme Weather Events Using Meteorological and Hydrological Indicators in the Laborec River Catchment, Slovakia

This study used the standardized precipitation index (SPI) and the standardized runoff index (SRI) to analyze dry and humid conditions in the hill-country catchment area of the Laborec River (Slovakia) over a period of 50 years (1970–2019). Analysis of the SPI and SRI over various time scales showed the occurrence of wet periods (index &gt; 1.0) that were associated with precipitation exceeding the long-term norm, and dry periods (index below −1.0), which were the result of small amounts of precipitation. Analysis of the correlation between the SPI and SRI on different time scales revealed that the catchment showed a weaker response to precipitation over short time scales (1 and 3 months) and a stronger response over longer accumulation periods (6, 9, and 12 months). The highest annual correlation coefficient (r = 0.72) was recorded between SRI-6 at the Humenne hydrometric station and SPI-9 at the Medzilaborce meteorological station in the upper part of the catchment area. The strongest annual correlation (r = 0.69) was obtained between the Izkovce and Kamenica stations in the lower part of the catchment area. As shown by the cross-relationships examined over different periods of accumulation of flows and precipitation, hydrological droughts appeared as a result of the occurrence of meteorological droughts with a three-month delay. The conducted analysis showed that in the case of the Laborec river catchment area, there was a strong correlation between the occurrence of meteorological drought and hydrological drought.

Reservoir Sizing at Draft Level of 75% of Mean Annual Flow Using Drought Magnitude Based Method on Canadian Rivers

On a global basis, there is trend that a majority of reservoirs are sized using a draft of 75% of the mean annual flow (0.75 MAF). The reservoir volumes based on the proposed drought magnitude (DM) method and the sequent peak algorithm (SPA) at 0.75 MAF draft were compared at the annual, monthly and weekly scales using the flow sequences of 25 Canadian rivers. In our assessment, the monthly scale is adequate for such analyses. The DM method, although capable of using flow data at any time scale, has been demonstrated using monthly standardized hydrological index (SHI) sequences. The moving average (MA) smoothing of the monthly SHI sequences formed the basis in the DM method for estimating the reservoir volume through the use of the extreme number theorem, and the hypothesis that drought magnitude is equal to the product of the drought intensity and drought length. The truncation level in the SHI sequences was found as SHIo [ = (0.75 ‒ 1) µo/σo], where µo and σo are the overall mean and standard deviation of the monthly flows. The DM-based estimates for the deficit volumes and the SPA-based reservoir volumes were found comparable within an error margin of ±18%.

Characterizing natural drivers of water-induced disasters in a rain-fed watershed: Hydro-climatic extremes in the Extended East Rapti Watershed, Nepal

Extreme climatic and hydrological events result in water-induced disasters and associated loss and damage of lives, livelihoods, and properties. It is related with various climatic, topographical, and anthropogenic factors, and therefore, expected to vary widely across the watersheds. This study characterized historical and projected future trends in climatic extremes, their spatial variations, hydrological extremes, and linkage between hydro-climatic extremes for a rain-fedExtended East Rapti (EER)watershed in Central-Southern Nepal. The watershed feeds intothe Gangesin the South Asia through the Gandakiriver. A set of 14 climate extreme indices, seven related to precipitation and seven to temperature, and eight hydrological indices were selected to characterize the extremes. Climatic and hydrological extreme indices were computed using RClimDex and IHA (Indicators for Hydrological Alteration) tools, respectively. Trends were calculated using the Modified Mann-Kendall test and Sens’s slope estimator. Relationship between hydrological and climatic extremes was evaluated by checking dates for rainfall extreme, hydrological extreme, and reported cases of flooding during that period. Results showed increasing trends in both precipitation and temperature extremes for the historical period (1980–2005) with a rate of 10–35% increase in RX1day (monthly maximum 1-day precipitation), 10–50% increase in R95p (very wet days precipitation amount) and 15–60% increase in warm nights from the base period until the mid-century. Hydrological alterations in terms of increasing extremes are also clearly visible in maximum flows, minimum flows as well as the shift in the day of maximum flow. Since, hydro-climatic extremes bear a direct relationship, future hydrological extremes, primarily floods, are expected to increase in future.

ASSESSMENT OF CHANGES IN HYDROMORPHOLOGICAL, HYDROLOGICAL AND HYDROCHEMICAL INDICATORS OF THE WESTERN BUG RIVER AND MEASURES TO REDUCE THEIR NEGATIVE EFFECTS

The methodology is considered and the assessment of hydromorological, hydrological and hydrochemical indicators of the river Western Bug iis carried out. The results of the study of sources of pollution of the river Western Bug, assessment of water quality, channel processes and mathematical modeling of its hydrological regime with developing of flood hazard maps and flood risk maps are presented. Measures are proposed to reduce the negative consequences of changes in the hydromorological, hydrological and hydrochemical indicators of the river Western Bug. &nbsp; &nbsp; &nbsp

User-oriented hydrological indices for early warning systems with validation using post-event surveys: flood case studies in the Central Apennine District

Abstract. Floods and flash floods are complex events, depending on weather dynamics, basin physiographical characteristics, land use cover and water management. For this reason, the prediction of such events usually deals with very accurate model tuning and validation, which is usually site-specific and based on climatological data, such as discharge time series or flood databases. In this work, we developed and tested two hydrological-stress indices for flood detection in the Italian Central Apennine District: a heterogeneous geographical area, characterized by complex topography and medium-to-small catchment extension. The proposed indices are threshold-based and developed considering operational requirements of National Civil Protection Department end-users. They are calibrated and tested through the application of signal theory, in order to overcome data scarcity over ungauged areas, as well as incomplete discharge time series. The validation has been carried out on a case study basis, using flood reports from various sources of information, as well as hydrometric-level time series, which represent the actual hydrological quantity monitored by Civil Protection operators. Obtained results show that the overall accuracy of flood prediction is greater than 0.8, with false alarm rates below 0.5 and the probability of detection ranging from 0.51 to 0.80. Moreover, the different nature of the proposed indices suggests their application in a complementary way, as the index based on drained precipitation appears to be more sensitive to rapid flood propagation in small tributaries, while the discharge-based index is particularly responsive to main-channel dynamics.

Особенности временной изменчивости содержания кислорода в зарослях Zostera marina Linnaeus, 1753 в бухте Воевода (Амурский залив, Японское море)

В настоящее время мелководные бассейны с лугами Zostera marina L. рассматривают в качестве поглотителей атмосферного углекислого газа, способных сдерживать увеличение его концентрации. Благодаря своей высокой продуктивности взморник выделяет в среду большое количество кислорода. Для установления особенностей проявления продукционной активности мелководных бассейнов, покрытых лугами Z. marina, на примере бухты Воевода (Амурский залив, Японское море) проведён мониторинг гидрологических и продукционных параметров с различными интервалами измерений. Наблюдения продолжались 8,5 мес. (22.09.2012–07.06.2013). В зарослях Z. marina на глубине 4 м измеряли температуру, солёность, флуоресценцию хлорофилла и мутность с помощью гидрологической станции Water Quality Monitor с интервалом 3 часа. Малоинерционным оптическим кислородным датчиком ARO-USB определяли концентрацию растворённого кислорода с интервалом 1 час. Установлено два типа изменчивости содержания кислорода в среде: 1) долгопериодная изменчивость, обусловленная сезонными изменениями среды; 2) суточная в период ледостава, определяемая интенсивностью проникновения фотосинтетически активной радиации в подлёдную воду. В осенний сезон отмечены низкие концентрации кислорода, достигающие уровня гипоксии. Для зимнего и весеннего периодов содержание кислорода находилось, как правило, на уровне 100–130 % от насыщения. Высокую суточную изменчивость наблюдали в период ледостава, в отсутствие снега. В феврале амплитуда суточных колебаний концентрации кислорода достигала 730 мкмоль·кг−1, с трёхкратным пересыщением по отношению к атмосферному O2. Установлено, что максимальная скорость продукции кислорода, отнесённая к 1 г сырой массы Z. marina, составляет 6,5 мг O2·час−1·г−1. Суточная динамика кислорода в морской воде проанализирована в связи с физиологическими особенностями Z. marina (воздухоносные полости в побегах играют важную роль в динамике кислорода в среде), а также в связи с короткопериодными приливами.

The age of dust—A new hydrological indicator in arid environments?

Abstract Dust plays important roles in the environment, and there has been much interest in the formation, provenance, and age of the world's dust deposits. Ongoing debates are concerned with the importance of glacial grinding versus eolian abrasion and fluvial transport in the formation of silt-sized particles. Short-lived uranium-series isotopes afford new insights because they can be used both for provenance fingerprinting and for constraining the integrated age of chemical and physical weathering and subsequent transport and storage of sediments. Here we present trace element and Sr, Nd, and U-series isotope analyses from a number of Australian dusts and suspended river sediments remobilized during floods a year later. The inferred ages of the Australian dust appear to be linked to aridification and the loss of inland megalakes ∼30–120 k.y. ago. This provides preliminary evidence that the age of dust may provide a new hydrological indicator in arid environments.

Water quality variation in tributaries of the Three Gorges Reservoir from 2000 to 2015

The Three Gorges Reservoir (TGR) underwent staged impoundment during 2003−2010. Periodic water impoundment included drainage (March to early June), low water level (June to August), impoundment (September to October), and high water level (November to February) periods. However, the impacts of the Three Gorges Dam (TGD) and impoundment on water quality of TGR tributaries remain poorly understood, especially in the long term and across the entire TGR drainage basin. Herein, water quality and hydrological indices of 27 tributaries, eutrophication of 38 tributaries, and pollution load of the TGR were determined during 2000–2015 to explore spatiotemporal variations in water quality. The results revealed slower flow velocity in tributaries and an extended residence time with the water level rising, and the water quality of tributaries was mainly affected by the mainstream backwater movement. Water quality was good in more than 60% of tested sites, had the best condition in the impoundment period, and it increased over time. Spatially, water quality in tributary upstream was better than in the backwater area, and worst in the tributary estuary. Among water quality indices, total nitrogen (TN) and total phosphorus (TP) were the key pollution indices, with median range of 1.619−2.739 and 0.088−0.277 mg/L, respectively. Additionally, water quality indices of TGR tributaries displayed temporal and spatial heterogeneity due to different hydrodynamic and pollution load conditions. A total of 38 tributaries displayed eutrophication, the frequency of blooms concentrated in spring and increased from the upper tributaries to the downstream area. These results expanded the theory of hydrodynamic variation and the associated evolution of the water environment after impoundment, could provide theoretical references for water quality management in river-type reservoir.

Features of water balance in the Selenga and Onon river basins during the formation of rain floods

Floods are characterized by non-periodic and short-term rise in the water level in the river, which can lead to catastrophic consequences and large material damage. The aim of this work is to study in detail the components of the water balance of the river basin, which affect the amount of flood runoff. The objects of study are the rivers of Eastern Siberia Selenga and Onon rivers. For the work, materials of long-term observations of the hydrometeorological network of the Trans-Baikal UGMS were used, as well as the database of the GPCC atmospheric precipitation climatology center. The methodological basis was a comprehensive hydrological and geographical analysis of the processes of flood runoff, namely the water balance method. In the course of the study, a geographical analysis of the factors of floods in the conditions of the steppe, forest-steppe and taiga zones of Eastern Siberia was carried out. For a thirty-year period of hydrometeorological observations in the basins of the Selenga and Onon rivers, graphs of changes in water discharge over time (hydrographs) were constructed and genetically related values of flood runoff and flood-forming precipitation were calculated. The unity of landscape characteristics and climatic features determine the hydrological indicators of the river in its different sections, which gives an overall picture of the hydrological indicators of the river network as a whole. According to the ratio of the maximum discharge of water of various origins, spring floods and summer floods, in the basin of the river Selenga and Onon groups of rivers were identified according to the prevailing origin of maximum flow. For the rivers of the Selenga and Onon basins, fluctuations in river runoff and atmospheric precipitation were investigated, and their relationships with the characteristics of atmospheric circulation were established. Difficulties in the analysis of hydrometeorological processes for the considered river basins are their transboundary location.

Water quality associations and spatiotemporal distribution of the harmful alga Prymnesium parvum in an impounded urban stream system

Abstract The Jim Bertram Lake System consists of several stream impoundments within the City of Lubbock, Texas (USA). Baseflow in the upstream reach is dominated by nitrogen-rich-treated wastewater. While toxic blooms of Prymnesium parvum have occurred in this system for ∼2 decades during fall or winter-spring, little is known about water quality variables that facilitate blooms or the alga’s spatiotemporal distribution. Water quality associations were examined monthly over a 1-year period. Total phosphorus was largely below the detection limit, suggesting that the system is phosphorus limited. Algal abundance was low during the assessment period and associations were determined using multiple logistic regression. Algal incidence was negatively associated with temperature and positively with organic nitrogen and calcium hardness. These findings conform with earlier reports but positive associations with the latter two variables are noteworthy because they have not been widely confirmed. Spatiotemporal distribution was evaluated in fall and winter-spring of three consecutive years. Prymnesium parvum incidence was higher in the upper than in the lower reach, and detections in the lower reach occurred only after a dense bloom developed in the upper reach contemporaneously with stormwater runoff-associated flooding. Thus, the upstream reach is a major source of propagules for downstream sites. Because urban runoff is a source of phosphorus and its nitrogen: phosphorus ratio is lower than prevailing ratios in the upper reach, what triggered the bloom was likely relief from phosphorus limitation. This study provided water quality, geographic and hydrological indices that may inform prevention and control methods for harmful algae in nitrogen-enriched urban systems.

Stream Health Estimation for the Plum Creek Watershed

Overall health of a stream is one of the powerful indicators for planning mitigation strategies. Currently, available methods to estimate stream health do not look at all the different components of stream health. Based on the statistical parameters obtained from daily streamflow data, water quality data, and index of biotic integrity (IBI), this study evaluated the impacts on all the elements of stream health, such as aquatic species, riparian vegetation, benthic macro-invertebrates, and channel degradation for the Plum Creek watershed in Texas, USA. The method involved the (1) collection of flow data at the watershed outlet; (2) identification of hydrologic change in the streamflow; (3) estimation of hydrologic indicators using NATional Hydrologic Assessment Tool (NATHAT) before alteration and after alteration periods; (4) identification of the most relevant indicators affecting stream health in the watershed based on stream type; (5) preliminary estimation of the existence of stream health using flow duration curves (FDCs); (6) the use of stream health-relevant hydrologic indices with the scoring system of the Dundee Hydrologic Regime Assessment Method (DHRAM). The FDCs plotted together for before and after the alteration periods indicated the likely presence of a stream health problem in the Plum Creek. The NATHAT–DHRAM method showed a likely moderate impact on the health of Plum Creek. The biological assessments carried out, the water quality data monitored, and the land cover during pre- and post-alteration periods documented in a publicly available federal document support the stream health results obtained from this study.

Modeling alterations in flow regimes under changing climate in a Mediterranean watershed: An analysis of ecologically-relevant hydrological indicators

The potential response of flow regimes to future climate has crucial importance for a variety of practical applications, such as sustainable water management and ecological asset preservation. For this study, multi-site investigations of alterations in flow regimes under projected climate change were performed for one of the largest watersheds in Morocco, the Bouregreg Watershed (BW). Future daily streamflow was simulated using the eco-hydrological model Soil and Water Assessment Tool (SWAT) forced by climatic data from CMIP5 model outputs. Simulations were carried out for two periods: 2035–2050 (2040s), and 2085–2100 (2090s) under two emissions scenarios: RCP4.5 and RCP8.5. Future streamflow regimes were examined in accordance with an Indicators of Hydrologic Alteration (IHA) analysis, while being confronted with baseline flow data. Mean temperature has been predicted to increase by up to 2.79 °C in the 2090s (RCP8.5), and a higher variability in rainfall regime is expected. The results indicate that, under future changes in climate patterns, flow regimes in BW will be altered. However, the extent of alteration will be reflected unevenly among the four streams of the study watershed. The IHA analysis revealed that most of the river network will experience both a decrease in monthly flow magnitude (mostly in November and December), and an increase (dominantly in February and March) when compared to baseline. The frequency of flash pulses, and the number of zero-flow days are also expected to increase. Most of the projected alterations were estimated to become very significant in the 2090s under the RCP8.5 scenario. The potential ecological implications were also analysed, and the most sensitive streams of BW were identified to guide local water planning and ecological preservation strategies.

Impacts of Global Warming of 1.5, 2.0 and 3.0 °C on Hydrologic Regimes in the Northeastern U.S.

Regional climate change impacts show a wide range of variations under different levels of global warming. Watersheds in the northeastern region of the United States (NEUS) are projected to undergo the most severe impacts from climate change in the forms of extreme precipitation events, floods and drought, sea level rise, etc. As such, there is high possibility that hydrologic regimes in the NEUS may be altered in the future, which can be absolutely devastating for managing water resources and ecological balance across different watersheds. In this study, we present a comprehensive impact analysis using different hydrologic indicators across selected watersheds in the NEUS under different thresholds of global temperature increases (1.5, 2.0 and 3.0 °C). Precipitation and temperature projections from fourteen downscaled Global Circulation Models (GCMs) under the representative concentration pathway (RCP) 8.5 greenhouse gas concentration pathway are used as inputs into a distributed hydrological model to obtain future streamflow conditions. Overall, the results indicate that the majority of the selected watersheds will enter a wetter regime, particularly during the months of winter, while flow conditions during late summer and fall indicate a dry future under all three thresholds of temperature increase. The estimation of time of emergence of new hydrological regimes show large uncertainties under 1.5 and 2.0 °C global temperature increases; however, most of the GCM projections show a strong consensus that new hydrological regimes may appear in the NEUS watersheds under 3.0 °C temperature increase.

Hydrological drought forecasting using multi-scalar streamflow drought index, stochastic models and machine learning approaches, in northern Iran

Hydrological drought is an environmental event that affects surface water resources such as surface runoff and reservoir levels and its prediction, can help the water managers to be aware of the future status of the region. This study aims to predict and evaluate hydrological drought in the southwestern margin of the Caspian Sea. For this, Streamflow Drought Index (SDI) is used as a multi-scalar hydrological drought indicator and calculated in time windows of 1, 3, 6, 9 and 12-month. In this study, time series stochastic models were used for the first time to predict SDI and compared with two black-box machine learning (ML) methods including Adaptive Neuro-Fuzzy Inference System (ANFIS) and Group Method of Data Handling (GMDH). The used data belongs to two rivers named Khalkaei and Pasikhan in Guilan province, and the period of 1986–2015 on a monthly scale. Autocorrelation and Partial Autocorrelation Functions (ACF and PACF) was used for selecting inputs among the series’ monthly time lags. The results showed that there are seasonal trends in SDI’s 1, 3, 6 and 9-month time windows; therefore, these time windows have better adaptability with the Seasonal Autoregressive Integrated Moving Average (SARIMA) model. But there is no seasonal trend in the 12-month time window (SDI12) series and the non-seasonal Autoregressive Moving Average (ARMA) model was found as the best choice for this time window. Among the models, the MLs (GMDH and ANFIS) had approximately similar prediction accuracies. Comparing the models indicate that the linear stochastic models in addition to the simplicity of use were significantly more accurate than the complex non-linear ML models. The current results suggest using the stochastic models for hydrological drought forecasting, in catchment areas.

ОПТИМАЛЬНАЯ ВЗАИМОСВЯЗЬ ГИДРОЛОГИЧЕСКИХ И МЕТЕОРОЛОГИЧЕСКИХ ПОКАЗАТЕЛЕЙ РЕК, ПРОТЕКАЮЩИХ В ЗОНАХ ГЕТЕРОГЕННОГО ГИДРОГРАФИЧЕСКОГО ЛАНДШАФТА

The article is devoted to a model study of the optimal relationship between hydrological and meteorological indicators of rivers flowing in zones with a variable hydrographic landscape. The aim of the work is to scientifically substantiate the conditions for achieving the extreme hydrometeorological indicators of river water flows in the studied hydrographic network of long rivers flowing through zones with a sharply changing landscape. The authors consider a heterogeneous model of river water flow, where in the entire length of the water mass movement, the average value of precipitation (and evaporation rate ( ) in some parts of the river vary naturally. The problem of calculating the optimal interrelation and, at which the newly introduced parameter, defined as the sum of the ratio of evaporation capacity to precipitation, would reach a maximum is stated. The solution of this problem by the variational method allowed to formulate and solve the problem of calculating the value of the index (sum of values of positive mean monthly temperature) at given values of the index k (), which would provide the specified maximum.The object of the study is rivers flowing in the zones of heterogeneous hydrographic landscape.The subject of the study is the relationship of hydrological meteorological indicators of rivers.The aim of the work is to scientifically substantiate the conditions for achieving the extreme hydrometeorological indicators of river water flows in the studied hydrographic network of long rivers flowing through zones with sharply changing landscape.Research methodology: the principle of determinism, objectivity, comprehensiveness, methodological triangulation. Research methods: phenomenological, analysis, generalization

Natural Suitability Evaluation of Habitat Environment in Transition Zone Based on GIS Spatial Analysis Technology—Taking Beichuan County as an Example

Analyzing and measuring the spatial distribution pattern of human settlement environment suitability in Beichuan County China is of great significance for optimizing population distribution and promoting human development and environmental protection. Based on the DEM data and other data of Beichuan County, this paper uses GIS and ENVI software to extract four spatial distribution data of vegetation coverage index, topographic relief, hydrological index and natural disaster risk, and the spatial distribution pattern of natural suitability of human settlement environment in Beichuan County was obtained through overlay analysis. The results show: 1) Most of the areas with small topographic relief are located in the southeast of the study area, which is New Beichuan County and Anchang Town and Yong’an Town. The vegetation coverage index in the eastern region is higher, while the vegetation coverage index in the western and other high altitude regions is lower because there are more grasslands. 2) From the perspective of spatial distribution, Beichuan County as a whole is rich in water resources in the central and eastern part of the county, while the west is short of water resources; Chenjiaba Township, Guixi Town and Old Beichuan County are located on the fault zone with high natural disaster risk, the natural disaster risk is high in Piankou Township and Xiaoba Town and Kaiping Township Area. 3) The human settlement environment index of Beichuan county is 19.72 - 85.25; The natural suitability is the highest in the southeast, followed by the central and western regions, and the worst is located in the Piankou-Xiaoba and Old Beichuan-Guixi fault zones. 4) The general suitable area in Beichuan County is the largest, accounting for 30.4% of the total area of the study area. More suitable area ranked second, accounting for 29.33%; critical fitness suitable area accounted for 17.87%; the area of suitable highly suitable area accounted for 14.06%, and the unsuitable area accounted for 8.32%. Reasonable and efficient development and use of local resources is an inevitable way for the sustainable development of Beichuan County.

Evaluation of Variability of Watershed Hydrological Partitioning: The Case of Mormora River, South Eastern Ethiopia

Water resources management in a watershed requires the quantification of the water potential. This is usually achieved by the estimation of the hydrological and meteorological characteristics of the watershed using observed data to carry out statistical estimates. Hydrological and meteorological data for the Mormora watershed were collected to analyze the hydrologic partitioning behavior of the watershed. The available data include a daily record of stream flow data from 1990 to 2007, a thirty years (1983-2012) monthly average precipitation at meteorological stations with in or near the watershed, and a 31 years (1981-2011) maximum and minimum temperature data at the same meteorological stations. The missed data of stream flow was in filled by simple regression method, and an outlier test, F-test, and T-test was computed for the data to check its quality. Necessary information about the geography of the area was obtained from LuLc, Soil, River, DEM, and climate map of Ethiopia, using ArcGIS software. Daily stream flow was converted to monthly scale and was partitioned to base flow and direct runoff using WHAT software. The maximum and minimum temperature data were used to estimate the potential evapotranspiration of the watershed using the 1985 Hargreaves equation. Average areal rainfall was estimated by Thiessen polygon method using ArcGIS software. Following these, the annual water balance of the watershed was analyzed using ‎water ‎balance ‎theory. The inter-annual variability of the water balance, and hydrologic indices were analyzed. The relationship between climate and landscape is also studied. The result shows that the Horton Index and Humidity Index of the watershed are relatively constant with a coefficient‎ of‎ variation, ‎Cv≤0.127.‎Finally‎conclusions‎are‎drawn,‎and‎the‎difficulties‎in‎ making hydrological and meteorological estimates in a watershed with little or no data are highlighted.