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Overview |
Crop Production |
Crop Pattern |
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Irrigation |
Soil Management | Precision Farming |
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GIS based diagnostic analysis of irrigation system performance assessment of Bhadra command area at disaggregated level
Digital map base preparation
The digital map base preparation is the first step towards the presentation of a GIS module for the irrigation water management. The map base is prepared by scanning the topo maps and the available revenue survey maps of the three distributaries and are reduced to a scale of 1:16000 to 1:8000 and are digitized edited and corrected with respect to topo maps. From the base of revenue levels, the base maps of reach and distributary level are prepared. The three map bases are stored in 3 levels of GIS. The revenue survey numbers were given a reference numbers in the GIS map base so that the data transfer can be done. A total of 878 polygons was formed in the base map and was given sequential numbering. The distributory map base consists of 3 polygons, each representing one distributary. Each polygon was given a reference for data transfer. Similarly, the reach map base consists of 9 polygons and was also sequentially numbered.
Sampling procedure for the selection of the farmers
The questionnaire designed is to be executed for the farmers in the 3 distributaries to get the attribute data. However, the total number of farmers in the 3 distributaries sum up to 1000 forcing the sampling to ease the complexity involved in the collection of data. The sampling done for the present study is a sort of stratified random sampling based on the yield variability such that the reaches having high variability in yield have more samples. Once the number of farmers in a particular reach were selected, the further selection was totally based on random sampling so as to see that the farmers selected were having their evenly located within a reach.
Detailed field survey
A total of 100 farmers were selected for the detailed field survey. Apart from this, the questionnaires to the agricultural and the irrigation authorities were also executed to the concerned officials. The questionnaire to the farmers was executed by the team comprising of 4 scientists, two having water resources background and other 2 with agricultural background. During the interview, questions on farmer’s personal views and wishes were noted and the farmer’s personal experiences with the dept. people were also noted. The collection of data from the irrigation department was done by distributing the questionnaires containing field conditions and field operations, to various officials at different Levels. Office data in the form of discharge data, structural condition records and other relevant data were also collected. The questionnaire to the officials of the agricultural dept. was administered through personal interview to the asst. agricultural director. The data such as soil fertility tests records for the areas covering the 3 distributaries was also collected.
Interpolation of physical resources data
As a first step, the ground reported yield was interpolated using the weighted average interpolation technique to generate a yield map. This ground report yield map is cross checked with the satellite-driven yield to:
- Prove the validity of yield model and
- Estimate the error of interpolation
Ground report travel time of flow was also interpolated to get a general picture of the canal condition, the moisture stress to get the general picture of the moisture stress,the fertilizer application adequacy (fig. 3) to find out the spatial variability of fertilizer application which gives an idea about the effect on yield and the involvement of farmers in various extension works.
Cluster analysis for socio-economic data:
Socio-economic factors such as farmer’s awareness, response and involvement in various NWMP works and views on the various govt. agencies are spatialised by performing a cluster analysis using theissen polygon method.
Using third method, the following maps were generated
- Farmers awareness to the various program’s under NWMP
- Match between water delivery schedule and agricultural operation
- Farmers involvement in irrigation scheduling
- Status of agricultural extension works
- Farmers views on the responsiveness on
the dept. of irrigation
These clustering enable the zonation of the study area into zones of farmer’s level of involvement which was studied for farmers awareness and responses to the various NWMP program’s. To obtain all the important information for the diagnostic analysis, the questionnaire based on the experience gained from the reconnaissance survey is designed for the irrigation officials, agricultural authorities and the farmers soak to obtain information from the relevant sources. Then systems such as digital base map preparation, sampling procedure for the selection of the farmers, detailed field survey, interpolation of physical resources data, cluster analysis for socio-economic data were performed.
Analysis on the primary and derived data
The data analysis was performed in two different environments. The primary or the first level analysis was performed in dBase III plus where the typical and most important trends for the performance of three distributaries were analyzed. The second level was in the GIS environment to cluster and group the inputs.
The following analysis were performed
- Water availability per unit area: Here the water at the take off point was taken as the conveyance and application losses were not measured. This analysis showed that water available per unit area for 15th distributory was less compared to the other areas. The further analysis was done now based on this as one of the main constraints.
- Principal Component Analysis: This was done to generate the indices showing the major causative component. Two types of indices namely Agricultural Productivity index (API), to study the effect of inputs on productivity and Farmers Involvement Index (FII) , to study the farmers participation In the irrigation activities.
- The API was derived based on the inputs related to water, seeds, etc. The Correlation of these factors with yield is taken weightage factor.
API = W (w1) + F (w2) + s (w3) + P (w4)
API = Agricultural Productivity Index
W = Water Availability (moisture stress);
F = Fertilizer application adequacy
S = seeds quality;
P = Pesticides usage
w1 to w4 = respective weightages
A closer look at the API map (fig. 3) in conjunction with the yield map reveals that the inputs used by in the 15th distributary were not good resulting in the low yield.
- The FII was calculated by taking into
consideration the awareness, response and involvement in the NWMP
works. The weightages for various factors applying Boolean logic.
The above table 2 shows the classes for the various factors and the weightages for various factors.
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