Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi

Öz

The data obtained from unit hydrograph are
being used to design of water structures like
bridges, culverts, dams, irrigation channels etc.
But when flow and precipitation data are
incomplete or not available synthetic unit
hydrographs are being used. The synthetic unit
hydrograph methods commonly used in our
country are Snyder, Mockus, DSİ synthetic
methods. The synthetic unit hydrograph method
which supposed by Dr. Nakayasu in 1940, is the
method which will be examined in this study.
Although this method has been commonly used in
Far East country it is not being used in our
country and European countries. In this study the
usability of synthetic unit hydrograph supposed
by Dr. Nakayasu in our country’s sub-basins is
examined. Unit hydrograph data of Kayraktepe,
Kirkyalan and Hamam which are in Goksu river
sub-basins are used for modifying given equation
of Nakayasu synthetic unit hydrograph methods.
Given equations by Nakayasu are modified by
using regression analysis and synthetic unit
hydrographs of these sub-basins are obtained by
using the new equations.
The obtained unit hydrographs and observed
average unit hydrographs are compared and Qp
values for Kayraktepe sub-basin is calculated as
109,253 m3
/s/mm, this value is calculated by a
0,769% error rate when compared to observed
value of 110,1 m3
/s/mm. The Qp values for
Kirkyalan sub-basin is calculated as 37,909
m3
/s/mm, this value is calculated by a 5,464%
error rate when compared to observed value of
40.1 m3
/s/mm and the Qp values for Hamam subbasin
is calculated as 45,555 m3
/s/mm, this value
is calculated by a 9,244% error rate when
compared to observed value of 41,7 m3
/s/mm.
The value of Tp is calculated for Kayraktepe as
28,037 hours, for Kirkyalan 22,476 hours, for
Hamam 23,347 hours. The error rates of Tp
values for these watersheds are respectively
0,132%, 2,164% and 2,721%.
The value of Tg is calculated for Kayraktepe as
21,637 hours, for Kirkyalan 16,076 hours, for
Hamam 16,947 hours. The error rates of Tg
values for these sub-basins are respectively
0,171%, 3,051% and 3,710%.
The value of Tb is calculated for Kayraktepe as
116,140 hours, for Kirkyalan 94,034 hours, for
Hamam 97.847 hours. The error rates of Tb
values for these sub-basins are respectively
0,121%, 1,384% and 2,153%.
When these all results examined, the Qp, Tp, tg,
T0.3, Tb parameters of unit hydrograph are
calculated with very low error rates by using
modified Nakayasu synthetic unit hydrograph
method. As a result, we can say that these values
are usable for Goksu River basin.