Forecasting water discharges of the river Marmarik (Armenia) according to the kinematic wave equation

Abstract

The article provides an overview of methods for short-term forecasting of water flow in mountain rivers based on physical-statistical and regression equations, conceptual approaches. Requirements for forecast models for the Armenian rivers are noted, which correspond to the kinematic wave model, but so far there are no forecast results for the Armenian rivers using this model. The purpose of the study was to test a mathematical model of a kinematic wave for a short-term forecast of water discharges on the mountainous Armenian river Marmarik. The model of a kinematic wave can be obtained after simplifying the model of channel runoff in a general form, i.e., after excluding from consideration deformations, local constant and variable backwaters from narrowing of channels, confluence of rivers, surge phenomena, and also after excluding the influence of the lower boundary condition, which is responsible for the characteristic of the diffusion spreading of the flood wave. A kinematic wave model was tested on the Marmarik River, which is an important water body in Armenia. We used series of observations of urgent water discharges during the spring flood from April 1 to June 30 for 2015—2018 at the top of the river Marmarik — Hankavan settlement, lower alignment — Aghavnadzor settlement and at the alignment on the main tributary of the river Gomraget — Meghradzor village. It was found that in the dynamic parametrization of the model, the anthropogenic impact should be introduced as an additional parameter. The obtained values of water discharges when making verification forecasts in the aggregate characterize the kinematic wave model as an effective approach according to the criteria for assessing the quality of forecast methods of the Hydrometeorological Center and Nash—Sutcliffe. The kinematic wave model is easy to use with a small amount of initial information without meteorological data, which will facilitate its implementation for practical applications.