ÖZETŞiddetli erozyon etkisi altmda bulunan Tortum gölü su toplamahavzasında sedimatasyon sorımu ve kontrolü üzerinde yapılan bu araştırmahavzasının gözlem süresine ait yıllık su potansiyeli ile toplamsediment taşınım miktarı saptanmıştır. Ayrıca hidrolojik verilerin değerlendirilmesiaçısından havzadaki önemli dereler için taşkın-tekerrüranalizleri yapı/arak elde edilen sonuçlar uygulama yonünden tattışı/mıştır.Havza karakteristiklerinin sedimantasyon üzerindeki etkilerininbelirlenmesiiçin havzanın jeolojik yapısı toprak dağılımı şimdiki arazikullanımı ye topoğrafik yapm ile meCra özelliklefi de incelenmiılir.SUMMARYARESEARCH ON THE SEDIMENTATION PROBLEM AND CONSERVATION OF TORTUM LAKE WATERSHED.This study is conducted in Tortumlake watershed which is under severeerosion. To determine the extent ofsedimentation and to give same recommeudationsfor the future landuse to slow the erosion.This watershed is on the northeastof Erzurum. Reseacrh area İs verysteep and covers the whole watershedhaving on catchment area of 1792km2.An observation post is located nearthe willage of Dikyar on theTortumriver and flow measurement taken forthe years of 1974, 1975 and 1976 byhydrometrie methods together requiredhydrologic data for the recIamationof the watershed. Stage-dischargecurves of the Tortum river for eachobservation year were plotted by usingthe data taken from tht; observationpost and water potentiaI is caldulatedby these curves. The mea-n annua( flowvaried 6-8 m3/sec the basin yield 4-6lt/sec/km2 and total annual now 196.106-257.10 6 m3 for the duration ofthe reseacrh. Expected mean flooddischarge of 82 m3/sec is being theproof of the very high erosion andsedimentati on.Estimate the total amount of sedimenttransported fro!J1 the basin.Suspanded sediment samples aretaken from the river by dept-integrationmethod. on the placeı where flowmeasurements are taken.A suspended sediment-rating curveıs determined from the relation betweenmean daily dischargeı and meandaily sediment for the dı;ıration of measurementsdone in the water years of1974, 1975 and 1976. Total amoiıntof sediment carried from the drainagebasin of 1457 km2 up from the placewhere- the measurehıents were takenwas found as 3,695.10,6 ton/year (1,759.10 6 m3/year) by using the methodsuggested by Miller (1951), analysis offlow-duration and sediment ratingcurve together. The method developedby Meyer-Peter and Müller (1948)for the estimation of bed-load is appIiestimatedannual bed-Ioad which inthe 16 %of suspended sedim'ent. Totalsediment carried from the basin is calculatedas 1,9.106 m3 and arerageannual sedİment produçtion rate ıs2,9.10 3 ton/km2.Those factors having an importantrole on the sediment produçtionsuch as geology, distribution of soilsand topography of the basin and' characteristicsof the stream bed are studied'to determine the effects of thebasin features on the sedimentation.Erosion control could deerease thedamage of sedimentation. Hence theinvestments done by state and agriculturalland would be protected agaİnstfloods. The filling of the lake bysediments alsa wi'll be ,prevented upto a certain degree. Socio-economicproblems of this reqion should be solvedto be able to reclaim the nnprodnctiveland and to prevent the floods.Reforesting of the former forest areasshould be first consideration; to aChierethis objective, state organizationsand local pıiblic should be tranied andurged for replanting. Restoration ofthe meadows is also another importantsubject, For this purpose npper basinshould be considered first.