Page 98 - 水利学报2021年第52卷第3期

Lateral distribution of the average water depth of the typical compound cross-section channel
under ice cover

1，2，3 1，2， 1，2 3
ZOU Dehao ，DAI Changlei ，GUO Xianfeng ，LU Jinzhi
（1. Institute of Water Conservancy and Electric Power，Heilongjiang University，Harbin 150080，China；
2. School of Hydraulic & Electric-power，Heilongjiang University，Harbin 150080，China；
3. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，
China Institute of Water Resources and Hydropower Research，Beijing 100038， China）

Abstract： The study of the horizontal distribution law of the depth averaged velocity of ice-coated rivers
with typical compound sections is of great significance for flood control and management. Based on the
SKM method， current study incorporated the double-layer hypothesis theory and introduced secondary flow
term into the Reynolds shear stress to build a quasi-two-dimensional model. This model takes into account
the effects of river bed friction， ice sheet resistance， lateral shear turbulence and secondary flow. Com⁃
pared with the experimental results of the corresponding physical model，the proposed quasi-two-dimension⁃
al mathematical model can reasonably predict the horizontal distribution of the depth averaged velocity and
river flow rate in each compound section. The mathematical model is able to capture characteristics of hori⁃
zontal distribution of the depth averaged velocity without solving complex equations simultaneously by com⁃
puter programming. This will provide significant guidance for the study of water flow characteristics of
ice-coated river channels with multiple sections.
Keywords：ice cover；complex section；velocity distribution；quasi-two-dimensional model
（责任编辑：李福田）

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Study on unit hydrograph model for rainfall-runoff simulation of urban roofs

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SHEN Hongbin ，XU Zongxue ，LI Lingjun ，HAO Xiuping
（1. North China University of Water Resources and Electric Power，Zhengzhou 450045，China；
2. Beijing Water Science and Technology Institute，Beijing Engineering Research Center
for Non-Conventional Water Resources Utilization and Water Saving，Beijing 100048，China；
3. College of Water Sciences，Beijing Normal University，Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology，
Beijing 100875，China；4. Bureau of Comprehensive Development，Ministry of Water Resources，Beijing 100053，China）

Abstract： According to the permeability characteristics， urban roofs can be divided into two types， imper⁃
meable roof and green roof. For the rainfall-runoff process on green roof，a unit hydrograph model was pro⁃
posed based on the saturated infiltration theory， where the thickness limitation of substrate material layer
and the influence of accumulated surface-water are considered. Meanwhile，Nash unit hydrograph model for
rainfall-runoff process on impermeable roof is introduced. Then， a unified unit hydrograph model for rain⁃
fall-runoff simulation on different urban roof types was developed， in which there are two parameters， re⁃
sponse rate and runoff generating time. For impermeable roof，model response rate is the reciprocal of con⁃
centration flow time. For green roof， model response rate is the reciprocal of stable infiltration time. Using
the proposed unit hydrograph model，rainfall-runoff processes on impermeable roof and green roof are simu⁃
lated. The results show that the estimated and measured values are consistent well. Comparison and analy⁃
sis on model parameters for different urban roof types show that the rainwater storage capacity of substrate
material layer plays an important role for the rainfall-runoff reduction effects of green roof. With the in⁃
crease of substrate material layer thickness， both the rainwater storage capacity and the first peak-flow re⁃
duction effect will increase， but later the peak-flow reduction effect will decrease， and the drainage time
of accumulated surface-water will be extended.
Keywords：impermeable roof；green roof；rainfall-runoff process；unit hydrograph；model；parameters
（责任编辑：韩 昆）

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