RESISTIVITY SURVEY AT KASIKIDZI ESTATE, KASUNGU

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Madeline Clarke
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1 18th December, 1972 FROM : R.B. BRADFORD, PELOCIST, P.O. BOX 27, ZOMBA. 7 : MR. K.F. WILDERSPIN, PRINCIPAL 1-oOLOGIST, P.O. BOX 27, ZOMBA. RESISTIVITY SURVEY AT KASIKIDZI ESTATE, KASUNGU INTRODUCTION An extended resistivity survey was made of the Kasikidzi Estate, Kasungu, from the 5th to 8th of December, The estate has been recently taken over by Mr. Atherson, as manager, on behalf of A.D.M.A.R.C. It is hoped to extensively cultivate tobacco and maize and, i2 possible, introduce a beef cattle herd. Before this can be done an adequate water supply must be found. AREA The estate covers some 4 acres to the east of the main Kasengu-pongwe road, 7 miles south of Kasungu. It lies approximately between 53 end 58 E and 46 to 51 N, adjacent to the watershed between the Bua, and Lingadzi drainage systems. (Fig.l). PRESENT WATER SUPPLY All farm needs at present are supplied by borehole P52 (hand pump); , which yielded 2 gph on test. This is reported to dry up quickly and is inadequate for the projected needs. Three sites were located, at approximately , in 197 by the geological survey. At least two were drilled privately but were 'dry'. The new manager persuaded a local 'water-diviner' from a nearby militate to locate new sites for boreholes. This was done and a site at was commenced by W.B.C., Lilongwe on the 5th December. This had reached almost 14 ft by the 8th before mechanical breakdown. Water was met at 9 ft which rose to 19 ft derived from a sequence of poorly-sorted, brown to white to prey, hornblendic-quartz sands. In addition a large 25 million gallon dam, is being built on the Chikoko river, at approximately The barrier is of puddle clay (?) and is reported to be clay sealed over moot of the dam. If this fills and water loss is not too great this should meet the demands of the tobacco and maize crops. However, the cost of pumping to the upper part of the area, where the beef cattle are to be fed, is too expensive. To reduce costs and for domestic use other boreholes are required in the central and upper parts of the estate. SURVEYS C.S.T. A survey was made initially in a south-east direction along the track that bisects the estate. This commenced some 3 yds south along the track for 2 yds to the offices. From this line other lines were set off at 218 m at 1 yds intervals to cover the three likely type of places where water could occur: across the 'flat' ridges, across the dambo sides and across the head of a smaller dambo. Readings were taken at 1 ft intervals. Four shorter lines were also made across low zones encountered some variation in readings was caused by surface sands. Depth Probes Five areas with readings of less than five K.O.C. were found. The low zone near the offices along the main track was not further examined, apparently coinciding with

2 2. the two dry boreholes drilled. Only one of the two zoneo near the Chikoko dambo was examined by depth probe. On depth probes A and B only Cooper's method was used but both Cooper and Wenner methods were used at C. SURVEY RESULTS The CeS.T. readings, in K.O.C., are given in Fig IIa and vertical profiles along the lines in Fig IIb gives the postulated areas having K.O.C. readings of less than 5, 5-7:.5, 7.5-1, and greater than 1. The area of greater than 1 on line (6) may be due to laterite interference. The zone in which the dry boreholes occur is rather narrow. At the site drilled on the water diviners suggestion readings are between The position of the three depth probes covering three zones of lees than 5 K.O.C. in given in Fig.IIb. Depth probe results are given in Fig.IV a--d. The results were as follows. d.p. A RB 156 (line (4) 29 w)cooper, d.p. B RB 154 d.p. C RB 155 (line (3) 13E) Cooper (line (4) 2W) Cooper and Wenner erawasinxesuxelteral*..., Cooper Wenner (ohm' P.9...eeasesnp -nvna*oteeapm5 l5 1.6 lo 6 5O lo CONCLUSIO The sandy drift tended to affect readinga. Five low zonso were:found by C.S.T. and three investigated by depth probes covering three likely sites for groundwater. Mean annual rainfall is only 3-35' and although no evaporation figures are given in Pike and Rimmington the Easunga area is probably semi-arid. Thus although there is a sandly soil the annual replenishment is low and water table deep (particularly being so near a major watershed) consequently, even though a reasonably good aquifer exists, yields will be low. Of the three peg sites RB 155 was recommended, particularly being near a quartzite (the position of which may not coincide with soil fragments due to soil creep). Any or all of the sites are to be drilled. It was suggested to Mr. Atherson, unofficially, that he made attempts to make maximum use of existing water enarces, including the use of monomolecular oil films over the dam surface, and the construction of well below the barrier to incercept the inevitable underfloor loss of water from the dam, Mileage travelled in survey: 757 miss. R.B. Bradford GEOLOGIST Time taken in survey, including travelling: 4 days.

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STARKE MINES. by MICHELLE ROGERS ~MMITCHEL/HON399/MICHELLE.HTM ORIGINALLY PUBLISHED IN

STARKE MINES. by MICHELLE ROGERS ~MMITCHEL/HON399/MICHELLE.HTM ORIGINALLY PUBLISHED IN STARKE MINES by MICHELLE ROGERS ORIGINALLY PUBLISHED IN HTTP://WWW.VALDOSTA.EDU/ ~MMITCHEL/HON399/MICHELLE.HTM ORIGINALLY PUBLISHED IN HTTP://WWW.VALDOSTA.EDU/ ~MMITCHEL/HON399/MICHELLE.HTM STARKE MINES