scholarly journals ДИФФЕРЕНЦИРОВАННЫЙ УЧЕТ ГЕОМОРФОЛОГИЧЕСКИХ УСЛОВИЙ ВОДОСБОРНОГО БАССЕЙНА С ИСПОЛЬЗОВАНИЕМ ПОРЯДКОВЫХ ХАРАКТЕРИСТИК ВОДОРАЗДЕЛОВ

Author(s):  
E.A. Shekman

Флагманом современной географии выступает моделирование географических систем и процессов их функционирования, базирующееся на огромных базах данных и алгоритмах многомерного компьютерного моделирования поведения сложных многосвязных систем. Сам процесс моделирования базируется на мощном аппарате математического анализа и статистической обработки базовых параметров объектов, на основе которых производится построение имитационных моделей их функционирования и развития. Речной бассейн является самым распространенным на поверхности суши природным объектом, обладающий отчетливо выраженными границами, структурной организацией, иерархией, относительной замкнутостью потоков вещества и энергии. При описании структуры водосборного бассейна речной системы традиционно применяются порядковые классификации. Порядковая классификация водотоков базируется на основополагающем свойстве речных потоков образовывать при последовательном слиянии древовидную структуру со ступенчатым нарастанием основных параметров системы. Стабильность структуры при этом поддерживается непрерывной деятельностью мощных потоков вещества и энергии. Широкое применение получила нисходящая порядковая классификация Р. Хортона 7, в основу которой легло положение о том, что неразветвленные элементарные водотоки сходны в разных условиях и должны иметь наименьший 1й порядок, образуя при слиянии водоток 2го порядка, в то время как водотоки 2го порядка образуют водоток 3го порядка и т. д. Также Хортоном, на основе анализа структуры речных сетей и их бассейнов были предложены законы соотношения основных характеристик водотоков разных порядков. Позднее порядковая классификация Хортона была доработана Стралером 6, который исключил понятие главной реки , которая на всем своем протяжении имеет максимальный порядок, хотя структурно состоит из множества разнопорядковых сегментов. Данные классификации сейчас принято рассматривать в едином контексте как классификацию ХортонаСтралера. Еще в XIX веке был высказан тезис о том, что водоразделы и тальвеги являются главными структурными линиями рельефа и находятся в тесной взаимосвязи 2, определяя распределение потоков вещества и энергии в водосборном бассейне. С использованием классификации водотоков ХортонаСтралера предложен принцип классификации водоразделов. На основе авторской методики обработки цифровых моделей рельефа (ЦМР) с использованием инструментов ГИС было апробировано использование порядковых характеристик водоразделов для получения детальной информации о вариациях основных характеристик однопорядковых элементов речной сети в зависимости от порядка водораздела в пределах бассейна реки Уссури.The flagship of modern geography is the modeling of geographical systems and the processes of their functioning, based on huge databases and algorithms for multidimensional computer modeling of the behavior of complex multiply connected systems. The modeling process itself is based on a powerful apparatus for mathematical analysis and statistical processing of the basic parameters of objects, based on which simulation models of their functioning and development are built. The river basin is the most widespread natural object on the land surface, which has distinct boundaries, structural organization, hierarchy, and relative isolation of matter and energy flows. In describing the structure of the catchment of a river system, ordinal classifications are traditionally applied. The ordinal classification of watercourses is based on the fundamental property of river flows to form a tree structure with successive merging with a stepwise increase in the main parameters of the system. The stability of the structure is supported by the continuous activity of powerful flows of matter and energy. The descending ordinal classification of R. Horton 7 was widely used, which was based on the proposition that unbranched elementary watercourses are similar under different conditions and should have the smallest 1st order, forming second order watercourses at the time how 2nd order watercourses form a 3rd order watercourse, etc. Also, Horton, based on an analysis of the structure of river networks and their basins, proposed the laws of correlation of the main characteristics of watercourses of different orders. Later, the Horton ordinal classification was finalized by A. Straler 6, who excluded the concept of the main river, which along its entire length has the maximum order, although it structurally consists of many differentorder segments. Classification data is now considered to be considered in a single context as the HortonStrahler classification. As early as the 19th century, the thesis was expressed that watersheds and thalwegs are the main structural lines of the relief and are closely interconnected 2, determining the distribution of matter and energy flows in the catchment. Using the classification of HortonStrahler watercourses, the principle of the classification of watersheds is proposed. Based on the authors methodology for processing digital elevation models (DEM) using GIS tools, the use of ordinal characteristics of watersheds was tested to obtain detailed information on variations of the main characteristics of singleorder elements of the river network depending on the order of the watershed within the Ussuri River Basin.

2019 ◽  
Vol 23 (11) ◽  
pp. 4491-4508 ◽  
Author(s):  
John R. Yearsley ◽  
Ning Sun ◽  
Marisa Baptiste ◽  
Bart Nijssen

Abstract. Aquatic ecosystems can be significantly altered by the construction of dams and modification of riparian buffers, and the effects are often reflected in spatial and temporal changes to water temperature. To investigate the implications for water temperature of spatially and temporally varying riparian buffers and dam-induced hydrologic alterations, we have implemented a modeling system (DHSVM-RBM) within the framework of the state-space paradigm that couples a spatially distributed land surface hydrologic model, DHSVM, with the distributed stream temperature model, RBM. The basic modeling system has been applied previously to several similar-sized watersheds. However, we have made enhancements to DHSVM-RBM that simulate spatial heterogeneity and temporal variation (i.e., seasonal changes in canopy cover) in riparian vegetation, and we included additional features in DHSVM-RBM that provide the capability for simulating the impacts of reservoirs that may develop thermal stratification. We have tested the modeling system in the Farmington River basin in the Connecticut River system, which includes varying types of watershed development (e.g., deforestation and reservoirs) that can alter the streams' hydrologic regime and thermal energy budget. We evaluated streamflow and stream temperature simulations against all available observations distributed along the Farmington River basin. Results based on metrics recommended for model evaluation compare well to those obtained in similar studies. We demonstrate the way in which the model system can provide decision support for watershed planning by simulating a limited number of scenarios associated with hydrologic and land use alterations.


2019 ◽  
Author(s):  
John R. Yearsley ◽  
Ning Sun ◽  
Marisa Baptiste ◽  
Bart Nijssen

Abstract. Aquatic ecosystems can be significantly altered by the construction of dams and modification of riparian buffers and the effects are often reflected in spatial and temporal changes to water temperature. To investigate the implications for water temperature of spatially and temporally varying riparian buffers and dam-induced hydrologic alterations, we have implemented a modeling system (DHSVM-RBM) that couples a spatially distributed land surface hydrologic model, DHSVM, with the distributed stream temperature model, RBM. The basic modeling system has been applied previously to several similar-sized watersheds. However, we have made enhancements to DHSVM-RBM that simulate spatial heterogeneity and temporal variation (i.e. seasonal changes in canopy cover) in riparian vegetation, and we included additional features in DHSVM-RBM that provide the capability for simulating the impacts of reservoirs that may develop thermal stratification. We have tested the modeling system in the Farmington River basin in the Connecticut River system that includes varying types of watershed development (e.g. deforestation and reservoirs) that can alter the streams’ hydrologic regime and thermal energy budget. We evaluated streamflow and stream temperature simulations against all available observations distributed along the Farmington River basin. Results based on metrics recommended for model evaluation compare well to those obtained in similar studies. We demonstrate the way in which the model system can provide decision support for watershed planning by simulating a limited number of scenarios associated with hydrologic and land use alterations.


2021 ◽  
Vol 13 (14) ◽  
pp. 2712
Author(s):  
Marta Ciazela ◽  
Jakub Ciazela

Variations in climatic pattern due to boundary layer processes at the topoclimatic scale are critical for ecosystems and human activity, including agriculture, fruit harvesting, and animal husbandry. Here, a new method for topoclimate mapping based on land surface temperature (LST) computed from the brightness temperature of Landsat ETM+ thermal bands (band6) is presented. The study was conducted in a coastal lowland area with glacial landforms (Wolin Island). The method presented is universal for various areas, and is based on freely available remote sensing data. The topoclimatic typology obtained was compared to the classical one based on meteorological data. It was proven to show a good sensitivity to changes in topoclimatic conditions (demonstrated by changes in LST distribution) even in flat, agricultural areas with only small variations in topography. The technique will hopefully prove to be a convenient and relatively fast tool that can improve the topoclimatic classification of other regions. It could be applied by local authorities and farmer associations for optimizing agricultural production.


Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 265
Author(s):  
Akarath Soukhaphon ◽  
Ian G. Baird ◽  
Zeb S. Hogan

The Mekong River, well known for its aquatic biodiversity, is important to the social, physical, and economic health of millions living in China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. This paper explores the social and environmental impacts of several Mekong basin hydropower dams and groupings of dams and the geographies of their impacts. Specifically, we examined the 3S (Sesan, Sekong Srepok) river system in northeastern Cambodia, the Central Highlands of Vietnam, and southern Laos; the Khone Falls area in southern Laos; the lower Mun River Basin in northeastern Thailand; and the upper Mekong River in Yunnan Province, China, northeastern Myanmar, northern Laos, and northern Thailand. Evidence shows that these dams and groupings of dams are affecting fish migrations, river hydrology, and sediment transfers. Such changes are negatively impacting riparian communities up to 1000 km away. Because many communities depend on the river and its resources for their food and livelihood, changes to the river have impacted, and will continue to negatively impact, food and economic security. While social and environmental impact assessments have been carried out for these projects, greater consideration of the scale and cumulative impacts of dams is necessary.


2014 ◽  
Vol 70 (4) ◽  
pp. 671-677 ◽  
Author(s):  
Xiaomin Ji ◽  
Youpeng Xu ◽  
Longfei Han ◽  
Liu Yang

Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.


2020 ◽  
Vol 12 (3) ◽  
pp. 941
Author(s):  
Di Liu ◽  
Hai Chen ◽  
Hang Zhang ◽  
Tianwei Geng ◽  
Qinqin Shi

Land surface elements, such as land use, are in constant change and dynamically balanced, driving changes in global ecological processes and forming the regional differentiation of surface landscapes, which causes many ecological risks under multiple sources of stress. The landscape pattern index can quickly identify the disturbance caused by the vulnerability of the ecosystem itself, thus providing an effective method to support the spatial heterogeneity of landscape ecological risk. A landscape ecological risk model based on the degree of interference and fragility was constructed and spatiotemporal differentiation of risk between 1980 and 2017 in Shaanxi Province was analyzed. The spatiotemporal migration of risk was demonstrated from the perspective of geomorphological regionalization and risk gravity. Several conclusions were drawn: The risk of Shaanxi Province first increased and then decreased, at the same time, the spatial differentiation of landscape ecological risk was very significant. The ecological risk presented a significant positive correlation but the degree of autocorrelation decreased. The risk of the Qinba Mountains was low and the risk of the Guanzhong Plain and Han River basin was high. The risk of Loess Plateau and sandstorm transition zone decreased greatly and their risk gravities shifted to the southwest. The gravity of the Guanzhong Plain and Qinling Mountains had a northward trend, while the gravity of the Han River basin and Daba Mountains shifted to the southeast. In the analysis of typical regions, there were different relationships between morphological indicators and risk indexes under different geomorphological features. The appropriate engineering measures and landscape management for different geomorphological regionalization were suggested for effective reduction of ecological risks.


2010 ◽  
Vol 11 (1) ◽  
pp. 122-138 ◽  
Author(s):  
Guoxiang Yang ◽  
Laura C. Bowling ◽  
Keith A. Cherkauer ◽  
Bryan C. Pijanowski ◽  
Dev Niyogi

Abstract Impervious surface area (ISA) has different surface characteristics from the natural land cover and has great influence on watershed hydrology. To assess the urbanization effects on streamflow regimes, the authors analyzed the U.S. Geological Survey (USGS) streamflow data of 16 small watersheds in the White River [Indiana (IN)] basin. Correlation between hydrologic metrics (flow distribution, daily variation in streamflow, and frequency of high-flow events) and ISA was investigated by employing the nonparametric Mann–Kendall method. Results derived from the 16 watersheds show that urban intensity has a significant effect on all three hydrologic metrics. The Variable Infiltration Capacity (VIC) model was modified to represent ISA in urbanized basins using a bulk parameterization approach. The model was then applied to the White River basin to investigate the potential ability to simulate the water and energy cycle response to urbanization. Correlation analysis for individual VIC grid cells indicates that the VIC urban model was able to reproduce the slope magnitude and mean value of the USGS streamflow metrics. The urban model also reproduced the urban heat island (UHI) seen in the Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature products, especially for the grids encompassing the city of Indianapolis, IN. The difference of the hydrologic metrics obtained from the VIC model with and without urban representation indicates that the streamflow regime in the White River has been modified because of urban development. The observed data, together with model analysis, suggested that 3%–5% ISA in a watershed is the detectable threshold, beyond which urbanization effects start to have a statistically significant influence on streamflow regime.


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