@article{nwisrl457,
           title = {Evaluation of Drop-Check Structures for Farm Irrigation Systems},
          volume = {29},
          number = {2},
         journal = {Transaction of the ASAE},
          author = {A.S. Humpherys},
            year = {1986},
           pages = {505--511,516},
             url = {https://eprints.nwisrl.ars.usda.gov/id/eprint/457/},
        abstract = {SMALL drop/check structures of various designs in
the 28 to 115 L/s (1 to 4 cfs) flow range were installed
in 1966 with their field performance evaluated in 1969.
They were again evaluated in 1984 after 19 years of
service. The parameters used to evaluate the structures
included cost, structural integrity, stability, hydraulic
performance and ditch erosion control capability. A
numerical rating was given in each category. A precast
concrete headwall with a rock-lined basin or plunge pool
was the most economical and one of the most effective
structures; however, special consideration must be given
to provide sufficient headwall length and cutoff wail
depth. Cast-in-place concrete structures were the most
stable and generally the most costly with variable
performances. Based on the study results and
observations, conclusions and recommendations were
made to improve the design of small drop structures.}
}