Surv y of WA 1 E ~ ~~~~S()lJ RCES Wrfll AERIAL Pll01, )GI{AilffS

V. V. Dhr a Narayana Centre Ar one Research lnstitutf', Jodlzp r

INTRODUCTION land resources of the Community Development Blocks by the Division of Basic Resources AERIAL PHOTO interpretation has become Survey of the Central Arid Zone Research an essential tool in modern land resources Institute, . surveys. The systematic interpretation techni­ The area chosen for the present investigation, ques developed by Buringh (1960), Platonenko in the Community Development Block, (1960), Meester (1961) and other earlier workers situated between latitudes 70°54' - 73°6' and are being increasingly applied in the location longitudes 24°30'-25°30', has a total popula­ of water bearing formations, mapping of regional tion of 46159 in 63 villages. In all there are ground water zones and surface water storage 1853 number of wells in use for drinking, stock sites. Miles (1951) and Parvis (1950) have water and for irrigation. Each village has one also accomplished the preliminary engineering or more surface tanks to serve the needs of the soil surveys and study of the significance of inhabitants for about 2 to 4 months. The drainage patterns by conveniently studying total irrigated area is 5578.59 ha. (Anonymus the above features on the aerial photos. Robert 1961). Jalore has an average monsoon rainfall et al (1957) have conclusively shown that air of 335 mm. The main rivers of the region are Photos offer inexpensive methods for the the Jawai and the Khari (tributaries of Luni prediction of ground water conditions of an river) which flow only during intense storms. area and location of sites for test wells. In In general the ground-water supply is quite U. S. A. Leuder (1959) checked the drainage satisfactory in the region except in hilly and conditions along some 80 miles of proposed duny tracts. light of way fo r a toll-road location in one of the most populous States in approximately Methods 3.5 days with the use of photographs alone and The technique of air photo interpretation 99% of the work was found to be in agreement involves the recognition of various photo with the field work which had taken several patterns and the logical deduction of their weeks. Much work, however, is needed to hydrological and engineering properties. It is improve the degree of accuracy of such predic­ necessary to analyse the significance of the tions. pictorial elements, such as tone, texture, shadow and outline, which in combination provide a These techniques were used for the first time comprehensive picture of ground conditions. in for the assessment of the water Detailed notes on interpretation of vertical air r~sources as part of the integrated survey of photographs recorded by Andrews (1940) are

7 a good guide. The aerial photographs do not A systematic analysis of aerial photos of the completely eliminate ground survey methods area to be surveyed is, therefore, necessary to but simplify the selection of representative plan, in advance, the field work. observation points. In the physical resource surveys aerial photos are used in three stages (ii) Field work : From the study of the aerial viz., (i) Photo interpretation and delineation photos, a note is prepared indicating the traverse of the different patterns and prediction of the routes, location of the query points and detailed characteristics of the different features of the observations to be recorded. Each traverse is patterns, (ii) field survey for verification and planned for a period of four days and the first correlation of the data with the patterns, and few traverses in a particular tract are so arranged (iii) final mapping and recommendations. A as to cover all the villages of the area to facilitate development block with an approximate area representative sampling of wells for ground of 1000 sq. km. is taken as the survey unit water. The following data are collected in the and is generally covered by 60 - 70 aerial field during the survey : photographs on a scale 1 : 42,200. Each stage of the survey is described below in detail. (1) Measurement of depths of water table and water column, determining oral (i) Preliminary Photo-interpretation : While quality of water, measurement of dis­ various features are shown on maps by means charge rate and collection of water of predetermined conventional signs, on air samples. photographs they appear as variations in tone or shade, which are an inherent characteristic (2) Determination of reduced level of the of the photographs themselves. These photo­ water table with altimeter. graphs when examined stereoscopically furnish a three-dimensional model of the region bringing (3) The approximate rates of recharge and out details which are normally unnoticed in a drawdown in different seasons and single photo. The stereoscopic view, particu­ approximate areas irrigated by the well. larly through a binocular attachment, facilitates the study of topography, drainage lines, waste (4) Collection of surface soil samples for lands, erosional features, different types of correlation with the irrigation waters. identical land patterns (with same shape, size and tone of individual fields), irrigated land (5) Data regarding water bearing material, patterns with wells and storage structures with whenever traceable. or without water. It is also possible at times to detect even such minute details like stoniness, (6) Present condition of the surface water soil texture, type of vegetation. The terrain storage tanks, depth of water, capacity characteristics, shading tones of vegetation, for storage, and the period for which land use and drainage patterns reveal the nature they are utilized. and availability of ground water. Normally, light textured and well drained soils will photo­ (7) Determination of proposed water graph light in tone, while poorly drained and storage sites and their suitability. fine textured soils will photograph dark in tone (Frost, 1953). The erosional features on the · Field traverse is conducted with the guidance aerial photos may also throw some light on soil of aerial photographs and topo-sheets on the patterns and rainfall-run off relationship. The scale of 1 : 126,520. The observation points irrigated land patterns give a clue to the extent such as wells to be sampled or surface tanks or of utilization and quality of water. Identifica­ storage sites to be surveyed are located on the tion of the drainage lines and demarcation of aerial photos with numbers for easy reference the catchments along with a knowledge of the at the time of final mapping. The notes and pre­ slope ami nature of the terrain greatly helps dictions drawn up during the preliminary photo to formulate proposals of surface water storage. interpretation are compared during field traver- ses. Doubtful points are scrutinized on the (iii) Dunes and dissected sands appear distinct­ spot. The boundaries of photo-patterns are ly in photographs indicating severe hazard of re-drawn or modified where necessary. wind and water erosion.

(iii) Final mapping : During the third stage, (iv) Gully eroded areas probably indicate after completion of field survey, soil and water high peak flow in the streams resulting from samples are analysed in the laboratory. A final intense flash storms. Drainage lines and slope interpretation note of the data is prepared for trends observed during preliminary photo inter­ map compilation. The available maps are on pretation are later verified in the field. Some the scale of 1 : 126520 and are used as the base changes in drainage lines are evident in the aerial maps. The delineations and markings on the photographs taken in 1958 as compared to aerial photos are transferred to the base map Survey of toposheets published in 1936. by using either 'Procota' drawing machine or by A stream near Bagra is shown in the pantograph for appropriate reduction of scale. topo-sheet as joining the Khari river while at The aerial photographs of Jalor block are present it is actually lead into the village tank at approximately of a scale of 1 : 42,200 thus Bagra. The course of some of the drainage needing 1/3 reduction for transfer to the base channels are blocked by blown sand and appear map. The hydrological characteristics are discontinuous. depicted by the following maps : The drainage characteristics of 7 catchments (i) Ground water table contour map, were studied to find out the general directional trend of streams, their disappearance, outlines (ii~ Ground water exploitation map, of water-shed areas and the slope of the land. The probable run off available for storage (iii) Ground water quality map, and along with the catchment areas and the proposals for surface water storage are reported in Table 1. (iv) Drainage map indicating the proposed surface storage sites. The proposed sites of surface water storage are near localities where ground water exploita­ Results and Discussion tion facilities do not exist due to low depth of Catchment drainage characteristics water table (36 m), and or by the adverse quality of water. All these catchments are classified (i) Heavy soils usually appear in uniform as bad from run off point of view due to the dark tone in the photographs indicating the low gently sloping terrain and or highly permeable rate of infiltration. These are the areas where blown sand cover and the uneven terrain, where dug-out ponds could be provided for surface surface detention in pockets reduces runoff. water storage as at Merku. The absence of Detailed investigations will, however, be nece­ well developed drainage lines or the presence of ssary to finalise the proposals of surface water long and straight streams in such patterns storage. indicates the level to gently undulating nature of the area and the possibility of water stagna­ Ground water quality and utilization tion during monsoon (Mollard, 1948). Irrigated land patterns appear on the aerial (ii) Occasionally cultivated fields (2 or 3 photographs in the form of dark patches with years) with freshly ploughed up land appear dark and white spots, which indicate the well as small dark pate es surrounded by a relatively and the thatched hut or threshing floor. The light toned patches in the same holding. One size of the dark patch surrounding the well of the reasons for such a wide-scale farming gives an idea of the quantity of water drawn practice in the region may be due to the low from the well. A bigger sized dark patch is water holding capacity of the soils because of generally indicative of the abundance of water low run off and high infiltration rates. in the well and a smaller sized dark patch may

9 Table !-Particulars of catchments for surface water storage

Catchment Catchment Rainfall Run-off in million Proposed S. No. Place of storage site Particulars from Aerial-photos. Area in (Monsoon) cu.m. (according measures hectares Cm. to Strange's Co- efficient for bad catchments)

1. Bagra Linear and disappearing chan- nels in the catchment except in the foot hill region 571.8 33.5 0.049 (i) Regular clearence 2. Between Bhagli and Linear and disappearing chan- 593.3 33.5 0.051 of stream channels. ~ Dhanpura. nels.

3. Dakatra Linear and disappearing chan- 789.1 33.5 0.068 (ii) Diversion of nels. flood flow into exis- ting tanks or propo- 4. Bhitala Angular channels but disappe- 308.8 33.5 0.026 sed dugout ponds. aring at times 5. Merku Linear and disappearing chan- nels with angular branch 424.9 33.5 0.036 (iii) Construction of streams near hills. diversion structures.

6. Kaniwara Linear channels. 116.1 33.5 0.010

7. Un Linear channels. 66.8 3.3.5 0.008 Table 2 : Correlation between aerial photo pattern and field data for water quality.

Aerial photo-Pattern Quality class Village areas £ PH Electrical conductivity Average Range Average Range Micromhos/Cm.

Wells with large Sweet water zone Sarupura, Sapni, Mithri, Wajanwadi, dark pattern Bhainswara, Bhagli, Pandgarh, Mailabas, Bhitala, Channa, Sena, Kondar, Raipuria Diladri, Santhu, Nun, Sarat, Narpara, Mandgaon, Jalore, Kurakhera, Mera. 8.12 7.7-8.55 1303 380-1980 - Wells with small Brackish water Rewat, Bokra, Mespura, Jalore, Leta, dark patches zone Sakrana, Godhan, Narawas, Dhan- pura, Bagra, Dudi, Dakatara, Akola, Channa, Bhagli, Takhatpura, Wajan- wadi, Odwara, Bilbara, Santipura 8.01 7.5-8.5 4199 2150-5600

Wells with no dark Saline water zone Deoki, Debhawas, Panwa, Desu, patches Bichwari, Dhanpura, Dhakatra, Degaon, Alwara, Akoli, Bagra, Nun. 8.08 7.7-8.7 10,910 6050-18600 Table 3. Correlation between aerial photo-pattern of sweet water zones and field data for well discharge

Aerial photo- Approximate Approximate Approximate S. No. Pattern. Name of the villages area irrigated hourly disch- daily discharge under well in arge in litres/ in litresjday Range hectares hour Average

1. Large patches Mithri, Wajanwadi, Sarupura, (dark tone) Sapni, Bhagli, Bhainswada, Sena, Raipuria, Bhakra. 2-4 11,250-22,500 54,000 1,48,500-1,17,000 -N 2. Medium patches Santhu, Bilbara, Sena, Channa (dark tone) Kondar, Mandgaon, Bagra, Degaon. 1- 2 6, 750-20,250 27,000 1,08,000-48,600

3. Small patches Jalore, Bokra, Bichawari, (dark tone) Narpara, Nun, Deladri, Kur- akhera, Alwara, Dhakatra, Bherat, Sarat, Bagra, Dudi. Less than 1 6,750-13,500 13,500 40,500-24,750 be due to the low availability of water in the wells actually sampled are correctly marked in well. In the irrigated land patterns, three the aerial photographs and these points are ~istinct types., viz., (a) a pattern with wells accurately transferred to the base maps Fig. 1. and large dark patches (b) a pattern with wells This is very helpful in preparing the maps of and very dark patches and (c) wells with no water table contours, quality and exploitation , dark patches at all are observed. Data from the zones. analysis of the water samples taken from the above three distinct patterns are given in Table 2. Summary

The table shows that the above land patterns This paper describes the application of represent sweet, brackish and saline water aerial photographs in water resources survey of zones respectively. This interpretation is further any region where aerial photos are used in confirmed by the fact that these photographs three stages viz., (i) Photo interpretation and were taken in the month of May, during which delineation of the different patterns and predic­ only irrigation with sweet water is practised for tions of the characteristics of different features of growing crops like jowar, lucerne and onion. the patterns (ii) field survey for verification and Irrigation with brackish water is practised to correlation of the data with the patterns and the bare minimum needs during summer which (iii) final mapping and recommendations. explains the small dark patches. Irrigation Stereoscopic studies, through a binocular, faci­ with saline water is done only in winter to grow litates the recognition of topography, drainage wheat and confirms the interpretation of third lines, waste lands, erosional features, irrigated pattern. The saline water zone may also contain land patterns with wells and storage structures some abandoned wells due to excessive salinity. with or without water. Normally, light textured There may, also, be some discrepancies in cla­ and well drained soils anpear in the aerial ssifying the patterns of wells with very small photos in a lighter tone while poorly drained dark patches as these may be due to low water and fine textured soils photograph dark in tone availability in sweet water zone or due to the indicating high and low rate of infiltration res­ brackish quality of waters. Such ambiguous pectively. On the basis of these and other cases are always checked up during field surveys characteristics such as trends of slopes and as in the case of Leta and Kondar, where this drainage lines, erosion features, the catchment pattern is due to brackishness and low availa­ classification for run-off and the surface storage bility of sweet water respectively. possibilities are predicted.

Since the aerial photographs were taken in The three distinct irrigated land patterns 1958, several new wells were dug in certain areas viz. , (i) wells with large dark patches (ii) wells and these were marked in the aerial photographs with small dark patches and (iii) wells with no during the field survey to indicate the availa­ dark patches in aerial photographs represent bility of water in abundance particularly in the sweet, brackish and saline water zones as con­ Wajanwadi-Mithri and Raipura regions. During firmed by the respective average electrical the preliminary interpretation stage these were conductivity figures of 1303, 4199 and 10, 910 classified as promising zones of water availabi­ micromhos. Further classification of the sweet lity. Computation of discharge from wells in water zone into good, average and low water the sweet water zone with different sizes of dark yield classes is made possible by the large, patches are reported in Table 3. medium and small dark patches in the aerial photographs which were found to have respec­ From the above data, it will be seen that tively the average daily watter yields of 54000, it is possible to estimate the quality and quantity 27,000 and 13,500 litres. Aerial photographs of well waters in the different aerial photo­ can also be used for preparing maps of water patterns with a reduced quantum of ground table contours and water quality by accurately survey by sampling wells in each of these patterns locating the wells and transferring them to 9Jl tPe b11sis of aerial photo interpretation. The base maps. Acknowledgments Leuder, D. R., 1959, Aerial photographic Inter­ pretation, Principles and applications, The author is very grateful to Dr. P. C. McGraw hill book Company 305-341. Raheja, Director and Dr. Y. Satyanarayan, Head of Division I, Central rid Zone Research Institute, Jodhpur for their most valuable Meester, T. De., 1961 , The application of air­ guidance and suggestions from time to time in photo analysis in a detailed soil carrying out this work. Acknowledgments survey in Tanganyika. I. T. C. are also due to Shri Pukhraj Bora, who was very Publication B10, Delft. helpful in laboratory analysis, computation of data and final map preparation. Miles, Robert D., 1951, Application of aerial photographs to Preliminary Engineering Soil References Surveys. Symposium on surface and sub-surface reconnaissance, Special Andrews, G., S. 1940, Notes on interpretation of technical Publication, No. 122, Am. vertical air photographs. For. Chron. Soc. Testing Materials pp. 57-72. 16, 202-215.

Anonymous., 1961, Statistics and Physiography Mollard, J. D., 1948, Air-photo mapping of (Hindi) Panchayat Samiti, Jalor Montgomery Country Soils for pp. 78. engineering purposes. Engineering experiment station Purdue University, Buring, P., 1960, Photo interpretation in the Lafayette, Indiana, Reprint No. 36 I. T. C. Soil Section, I. T. C. Publica­ pp. 223 - 266.

tion B 2, Delft. Parvis M., 1950., Drainage pattern significance Frost, R. E., 1949, The use of air-photos in soil in air photo interpretation of soils and studies. Purdue airphoto interpreta­ rocks, Bulletin 28, Soil exploration tion Lab., Purdue Univ., Lafayette, and mapping Highway Research Ind. (1949). Board, Washington D. C., Nov., Howe Robert, H. L., Harvey R. Wilke and Don pp. 36 - 62. E. Bloodgood, 1956, Application of air photo interpretation in the loca­ Platonenko, M.A., 1960, Accuracy in mapping tion of ground water. Journ. Amer. soils from aerial photographs. Tran­ Water Works Assoc. 48 (11) : 1380 slation Soviet Soil Science, 1960 -1390. No. 1 (May 1961).