Document Type : پژوهشی
Authors
1 Assistant. prof. Geomorphology , Msc. geology Soil Conservation and Watershed Management Department Agriculture &Natural Resources Research Center of East AzerbaijanTabriz,Iran
2 Research Associate Research Institute of Soil Conservation and Watershed Management, Agricultural Research, Education and Extension Organization, Tehran
3 Master in Geomorphology - Agriculture Natural Resource Research Center of East Azarbaijan
Abstract
1-Introduction
The common method of supplying water for agricultural purposes is flood irrigation used in semi-dry areas from past times. Flood utilization has long been one of the common water supply methods among farmers in dry areas of the world due to inaccessibility to sustainable surface or underground water resources. In North America, Indians have used simple flood irrigation methods for centuries (Hudson, 1975). The studied area is located at 110km from the center of the province, north of Uremia Lake and the drainage basin surrounding Tasoj city at 45°18' to 45°33' eastern longitude 38°20' to 38°24' northern latitude. The area includes ten sub-basins overlooking the city of Tasuj and the villages of Angashtjan and Amstajan, and its area is 9616.79 ha. The average height of the area is 1700m with an average rain of 271mm in 20 years and an average annual temperature of 13.4°C. The region is climatically affected by polar air from the north, polar sea from the northwest, tropical climate from the south. The region's climate is cold semi-arid, and the rainfall regime is in the Mediterranean. The main feature of this regime is intense rainfall, spring rainfalls, and intense snowing in winters, along with several months of drought in summer and late spring. The land use of this region includes farming gardens 938ha, irrigated aquaculture 2050ha, and dry farming 420ha. The cultivation pattern of farms and gardens mostly includes apple, walnut, Elaeagnus Angustifolia, almond, cherries and alfalfa, wheat, barley, and chickpeas that are the farming lands with aridity problems. Angoshtjan and Amstejan ponds and watersheds have two U.R.F upper Miocene geologic formations and the equivalent formations of Qom with marl, limestone, and sandstone deposits that produce high sedimentary floods (Habibzadeh, 2018). One of the main objectives of flood distribution projects is the improvement of the status of natural resources in flooding plains on the alluvial fans of the outflow of the problematic
watershed, the storage of precipitation, supply of underground sources, supply of required water for crop and farming, quantitative and qualitative changes of vegetation, changes in plant composition and increase of plants for feeding and increase of soil fertility. Lashanizand et al. (2010) studied the changes in surface water quality of Kashkan basin due to periods of water scarcity and watery and for this purpose, 12 parameters of water quality and discharge statistics of eight hydrometric stations in 30 years and concluded qualitative changes from The ascending and descending trends follow the periods of watery and aridity. The purpose of this study, while presenting a qualitative analytical method of floods, is to use floods in agricultural water supply in the agricultural plains north of Lake Urmia.
2-Methodology
The research project investigating the effects of incoming flood quality on flood spreading performance was carried out by the author to create model areas for flood exploitation for agriculture, promotion, and development of flood distribution systems in arid and semi-arid regions. Samplers were installed along the flood paths of the Angoshtjan and Amstejan sub-basins at the entrance of the plain and in three locations of impoundment system, above and below these systems with gages. After the installation of samplers, the flood sampling was done to this end, sampling was performed three times in 2011, two times in 2012 and one time in 2014; the number of samples to be taken was determined based on the flood discharge and the height of samplers and sent to the laboratory for analysis. The results related to the differentiation of the sampling location have been classified using Model and Wilcox diagram (Habibzadeh, 2017).
3-Results and Discussion
The main limitation in agriculture, especially in arid and semi-arid regions, is the supply of water needs. In such areas, water is the basis for planning for agricultural development. Every year, much water flows out of reach in the form of runoff or floods and causes much damage to agricultural lands, residential lands, and roads (Mesbah and Negahdar, 2015). According to the purpose of the research, it was necessary to prepare information about the amount of rainfall and floods in the region. For this purpose, the amount of flood extraction was calculated and collected based on 20-year statistics of rainfall and floods in the region. The average monthly rainfall and flood storage are shown in Table 1. Flood samples were sent to the laboratory for qualitative analysis during six floods over three years. Laboratory analyzes including salinity, acidity, anions, and flood cations were performed. The lowest salinity, or EC, is related to the flood of the Amstajan river with 345 μm /cm, and the highest is related to the flood of the Angoshtjan river with 799μm / cm.
Table (1): Average monthly flood rate in Tasuj study catchments (2000-2020)
Month
Precipitation
mm
Flood storage
m3
Flood
%
April
39.6
53054.0
39.1
May
51.7
51005.2
37.6
June
13.8
2875.0
2.1
July
6.4
865.7
0.6
August
4.1
1432.7
1.1
September
9.3
28.6
0.0
October
11.7
2134.2
1.6
November
35.5
5432.1
4.0
December
25.4
0.0
0.0
January
14.2
0.0
0.0
February
28.2
0.0
0.0
March
29.6
18698.7
13.8
269.5
135526.2
100.0
4-Conclusions
In this project, to access the 2.5 million m3 outflow flood of Amstejan and Angoshtjan villages, the qualitative analyses of flood samples have been done based on Wilcox, Piper, and Stiff hydro-chemical diagrams. The mean electric conductivity in Amstejan sub-basin floods is 350mho/cm, and for Angoshtjan, the sub-basin is 600 mho/cm. The floods have relatively alkali acidity or neutral. The highest values, 8.06 and 8.04, are related to the inflow flood of the reservoir of flood collection. The quality of floods in terms of irrigation water classification of Wilcox method, where salinity and sodium rate are the most important criteria, is mostly in the C2S1 area. In terms of classification of irrigation water, C2, water with medium salinity that can be used for plants with medium tolerance to salinity, S1 is low sodium water which is good for irrigation of all types of soils and is not risky; therefore, they are good waters for agricultural purposes.
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