Chemical composition of geographical types of the small river basin waters (Central Sikhote-Alin Mountains,Pacific Asia)

In the article, the results of field observations of the chemical composition of the small river basin waters obtained during warm periods in 2011–2012 are presented. Seven basic geographical types of water were investigated, namely, cyclonic rainfall, rainstorm, throughfall, subsurface soil flow, low water flow (specific discharges of waters do not exceed 2.5 L/s km²), low floods (peak specific discharges are from 2.5 to 16 L/s km²) and medium floods (peak specific discharges are from 16 to about 100 L/s km²). A result of the interaction between the rain water and landscape constituents is that all examined natural waters differ to the maximum extent in the anionic composition. A chemical type of stream waters is sufficiently stable; it is formed predominantly within the soil-ground cover and does not change with increase in flow rate.     

Estimating distribution parameters of extreme hydrometeorological characteristics by <Emphasis Type="Italic">L</Emphasis>-moments method

L-moments method is briefly described and compared with classical methods of moments and maximal likelihood. Algorithms are given for calculating parameters of some distributions widely used in engineering hydrology, meteorology, etc. The advantages of L-moments method relative to alternative methods are analyzed for several examples.     

Forecast of the rainfall flood hydrograph on the Far East Rivers

A procedure of forecasting the hydrograph of rain-fed rivers four to six days ahead from precipitation data is considered. The forecast procedure is based on basin-indicators. A new element of the procedure is an original model of the flood cycle in a small river basin used as a first element of the entire rainfall-runoff transformation scheme. Application is discussed of the complete prediction algorithm, given the necessary number of basin-indicators, and the incomplete algorithm that is adapted to a real state of the observation network in different ways.     

A Model of Mixing of Four River Runoff Recharge Sources Using Hydrochemical Tracers in the Problem of Hydrograph Separation

Methods for the analysis of the formation of river water chemistry based on mixing models are discussed. An analytical solution for a mixing model of four recharge sources is given along with the results of its adaptation based on the materials of hydrochemical and hydrological observations over 2013 and 2014 in drainage basins in Primorski Krai. The analysis and calculations revealed four components of river recharge in these years: rainwater, two types of subsoil water, and groundwater, the latter forming the base runoff. The estimates of the mixing model with four sources and its tests showed a high quality of modeling.     

Classification of river basins and hydrological regionalization (as exemplified by Japan)

A set of problems related to formation of areas homogeneous in hydrological aspect is considered. A methodology of regionalization is proposed. New analytical methods of the methodology are intended of solving such problems as (i) the problem of regionalization and (ii) the problem of constructing of a classification for river drainage basins. Efficiency of the methods proposed has been tested on the problems, which arise in the process of constructing classifications for river drainage basins, and also on the problem of territorial regionalization of Japan islands. Investigations, which presume obtaining a set of morphometric and hydrographic characteristics of catchment areas, allow one to study conditions of extreme inundations. It has been discovered that boundaries of the areas have striking similarities in the spatial location of geological structures. Furthermore, these are coincide with the boundaries of the main tectonic fields.     

Analysis of natural tracers and genetic runoff components in mixing models: Case study of small basins in Primor’e

An algorithm has been proposed for the diagnostics of the number of runoff genetic components and reliable chemical tracers in mixing models. The algorithm is applied to the analysis of data of hydrological—hydrochemical monitoring obtained during experimental studies on small watersheds in Elovyi Creek basin. The number of stable genetic runoff components and the list of tracers can vary from year to year depending on the state of moistening on the watershed.     

The Forms of Linear Structure of Overland Flow in Medium-Height Mountain Regions: Case Study of the Sikhote Alin

Water Resources - Large subsurface streams on steep slopes have stable positions with distinct catchment areas (drainage basins), linear shapes, and lengths of tens and hundreds meters. They form a...     

Types of probability distributions in the evaluation of extreme floods

The development of an optimal scheme for evaluation of maximal water discharges is discussed, including adequate probability distribution laws, an effective procedure for their approximation based on observational data, and reliable goodness-of-fit tests for analytical and empirical distributions. One-dimensional probability distribution laws are systematized. Promising distributions were identified, including generalized distribution of extreme values, lognormal distribution, Pearson type V power distribution, and GPD, for evaluating maximal discharges. The available methods for approximating analytical curves, including the up-to-date method of L-moments are considered. Parameter estimation algorithm based on L-moment method for Pearson type III distribution is considered. Pearson type III distribution, lognormal distribution, GEV, and GPD are compared in the approximation of maximal water discharges in rivers of Austria, Siberia, Far East, and the Hawaiian Islands.