Research in Urumqi

Objectives

  1. Clarify the hydrology of the Yerqiang Basin
  2. Estimate the human water use and clarify artificial (man-made) water cycle of the basin
  3. Assess the impacts on hydrological processes and water resources from Global Change, primarily due to climate change and human water usage (population growth, industrialization, agriculture expansion, etc)
  4. Propose water management plans utilizing existing water management infrastructure (diversions, storages and pumping facilities) to address these challenges.

Methodology

  1. Construct a detailed hydrological and human water activities model
  2. Calibrate and validate the model
  3. Scenario Analysis
    1.  Assess the future climate change impacts on weather and hydrology
    2. Assess future water consumption and demands and their impacts on hydrology processes and water resources management

Procedure

  1. Conceptual representation of the catchment water balance to be prepared with inputs, output, consumptions and storages clearly identified and their relation clarified.
  2. First use a process model, such as SHER model, which is physically based, distributed and can well represent and extend to cover both natural and artificial water cycles.  Then specific fully distributed models, such as MODFLOW for ground water model be used for specific sectors and processes.
  3. The human water consumption model will be based on a water demand model and field surveys to quantify actual consumption based on these demand models.
  4. For the model, first a GIS of geophysical data will be prepared.

 i.     DEM

ii.     Land use

iv.     Groundwater:  Aquifers, and aquitard extents, Transmissivity and storage coefficient distribution

v.     Glacier boundaries

Second a GIS to model human water consumption need to be prepared.

 i.     Population and industries distribution

ii.     Water consumption per land use

iii.     Canal network and control structures

iv.     Water storage facilities and operational rules (gates, pumps, diversions)

  1. Hydro-meteorological input data for the model

i.     Rainfall distribution

 ii.     Snow cover and temperature distribution

 iii.     Wind speed, direction, net radiation for evaporation computations iv.     Ground water withdrawals

  1. Hydro-meteorological input data for the model calibration and validation

 i.     Stream flow measurements at major confluences

ii.     Water levels and H-Q relation for storages (dams and lakes)

iii.     Groundwater level measurements

Research Background and Justification

 Yerqiang Basin is unique in China, not only because it is an important source of largest dryland Lake in China, but also because of its unique hydrological characteristics and the extensive human interventions in the basin. Understanding the hydrological processes and their inter-relations is extremely important to anticipate the impacts from Global Change, especially from Climate Change and expansion of human activities on hydrological processes as well as water resources. It is important to design appropriate adaptation strategies for these changes while preserving the fragile hydrological balance and preserving ecosystems and their services.

 So far a comprehensive modeling approach has not been undertaken to clarify the inter-relations among different hydrological processes and human activities on the hydrological cycle. In this research we will develop a hydrological model comprising of Glacier snow melt, rainfall-runoff and ground water recharge and discharge processes coupled with the water supply, consumption and drainage human activity model to support the above needs.

Modeling Approach

The initial process model will use both storage and water pressure as state variable and comprise of surface water balance model consisting of both pervious and impervious zone storage and runoff, kinematic wave stream flow model, simplified Richards’ equation based infiltration and interflow processes, and the Darcy law based ground water flow and percolation to deep aquifers.  Snow melt model based on a modified degree day model and evaporation model based on  potential evaporation, plant evapotranspiration and soil layer evaporation will be coupled with the rainfall input data to the model.

The artificial water cycle (man made) will be modeled with the unit impulse function concept, where input is routed with a storage-function type models based on the water supply-consumption-discharge relation of specific water utilizing sector (domestic, agricultural, industrial) 

The ground water needs to be modeled with actual aquifer distribution and the aquifers may extend beyond the surface catchment. The recharge to the external segments of the aquifers need to be modeled through a lumped recharge model based on landuse type .

Climate Projections and Downscaling

Initially an assessment will be made to identify appropriate GCM from the family of CMIP5 models based on their performance from 1980-2000 period by comparing with the rainfall and temperature observations in the catchment. The selection will be based on the ability of each model to reproduce the local climate.  CODEX data sets availability for the selected model will be checked to obtain high resolution future climate rainfall and temperature time series. If not available SDSM model will be used for downscaling climate projection data for future scenarios.