East Asia and Western Pacific METEOROLOGY AND CLIMATE

crop growth, and desert) and climatological variables.
(3) To investigate the concentration and size distribution of dust
over desert and its effect on climate.
(4) To study the water requirement by main crops and the
techniques of water-saving irrigation in Heihe district and to
estimate the water resource, its utilization ratio and the
agricultural potential in Hexi Corridor, Gansu Province in western
China.
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II. Experimental Area
Heihe river basin is located in the arid region in the midlatitude
and one of the most important irrigated agricultural region
in northwest China with great agricultural potential. The annual
rainfall of the region is 100—150 mm.
The experimental area (99°30 f —101 o OO f E, 38°40 f — 39°40 f N) consists
of a rectangle with an area of 70km*90km and a triangle with an
average elevation of 1500m above sea level as shown in Fig. 1. South
to the experimental area is the Qilian mountain, the northern edge of
the Qinghai-Xizang (Tibet) Plateau. The Heihe river originates from
the glacier over the Qilian mountain. The northern boundary of the
experimental area stretches into the desert. The Heihe river flows
through the experimental area. North of the river, about half of the
experimental area is desert, some of which is Gobi. The south area of
the river is mostly flat irrigated cropland with Gobi in it. The main
crops in the area are wheat and maize. The farmland is bare in
winter.
Within the area, there are three standard meteorological stations
of the State Meteorological Administration (SMA), four hydrological
stations and an experimental station of the Lanzhou Institute of
Desert (LID) of the Academia Sinica, located in Linze County.
Five sites (Fig. 2) have been selected as basic experimental
stations. They are located in Zhangye city(cropfield with wheat),
Linze county (cropfield with maize), Pingchuan desert experimental