Effects of different spatial configuration units for the spatial optimization of watershed best management practice scenarios

Liang-Jun Zhu, Cheng-Zhi Qin*, A-Xing Zhu, Junzhi Liu, and Hui Wu



Different spatial configurations (or scenarios) of multiple best management practices (BMPs) at the watershed scale may have significantly different environmental effectiveness, economic efficiency, and practicality for integrated watershed management.

Several types of spatial configuration units, which have resulted from the spatial discretization of a watershed at different levels and used to allocate BMPs spatially to form an individual BMP scenario, have been proposed for BMP scenarios optimization, such as the hydrologic response unit (HRU) etc. However, a comparison among the main types of spatial configuration units for BMP scenarios optimization based on the same one watershed model for an area is still lacking.

This paper investigated and compared the effects of four main types of spatial configuration units for BMP scenarios optimization, i.e., HRUs, spatially explicit HRUs, hydrologically connected fields, and slope position units (i.e., landform positions at hillslope scale). The BMP scenarios optimization was conducted based on a fully distributed watershed modeling framework named the Spatially Explicit Integrated Modeling System (SEIMS) and an optimization algorithm (i.e., NSGA-II, short for Non-dominated Sorting Genetic Algorithm II). Different kinds of expert knowledge were considered during the BMP scenarios optimization, including without any knowledge used, using knowledge on suitable landuse types/slope positions of individual BMPs, knowledge of upstream–downstream relationships, and knowledge on the spatial relationships between BMPs and spatial positions along the hillslope.

The results showed that the more expert knowledge considered, the better the comprehensive cost-effectiveness and practicality of the optimized BMP scenarios, and the better the optimizing efficiency. Thus, the spatial configuration units that support the representation of expert knowledge on the spatial relationships between BMPs and spatial positions (i.e., hydrologically connected fields and slope position units) are considered to be the most effective spatial configuration units for BMP scenarios optimization, especially when slope position units are adopted together with knowledge on the spatial relationships between BMPs and slope positions along a hillslope.

Software availablility


Our paper entitled “A modular and parallelized watershed modeling framework” has been published in Environmental Modelling & Software on Sep.26, 2019. Thus the 33rd citation should be updated as:

Zhu, L.-J.; Liu, J.; Qin, C.-Z.; Zhu, A.-X. A modular and parallelized watershed modeling framework. Environ. Model. Softw. 2019, 122, 104526. Google Scholar CrossRef


After the addition of one citation during the revision stage, several mark numbers in the main text are missed to be updated. We apologize for the inconvenience caused by these misnumbered references.

Here is the corrigendum:

  • Section 2.4, the second paragraph, at the end of the fifth line, [39] should be [40];

  • Section 2.6, [33] in the second paragraph should be [34] which appears in lines 1, 13, and 18;

  • Section 2.6, the second paragraph, at the end of the first line, [2,16–18] should be [2,17–19];

  • Section 2.7, the last sentence of the first paragraph, [32] should be [33];

  • Section 2.7, the fourth paragraph, at the end of the fifth line, [33] should be [34].

We sincerely hope that people who are interested in our paper could download the updated and corrected version by this link.

Review history

  • Submission: 2018-12-22

  • English editing by MDPI: 2018-12-20

  • Submission received and Pending review: 2018-12-22

  • Under review: 2018-12-24

  • Pending decision: 2019-01-15

  • Accept after minor revision (Academic Editor): 2019-01-18

    • Review by academic editor: I believe the work presented here has scientific merit and very useful to the professional modeling community. Please refer to the comments made by reviewers 1 and 2 and make necessary revisions to the manuscript.

  • Major revision (Assistant Editor): 2019-01-20

    • Reviewer #1: This is a well-written and well-organized manuscript evaluating the effects of spatial configuration units of BMPs on soil loss using optimization methods using the modeling approach. The authors have used the spatial configuration units as a basis to evaluate where in the watershed BMPs should be placed to reduce its impact on downstream water quality. This paper is of great benefit to the scientific community in general, and to the forest and agricultural managers who will be relying on modeling tools to support management activities under future land use and climate change. The introduction is very well written. The authors give a comprehensive of BMP optimization schemes previously used in such studies and their limitations. The goal and specific questions are clearly defined. The method section describes their approach well and aligns well with results section. The QSWAT model used for this study could prove to be a promising tool for decision making. I have minor editorial suggestions.

    • Reviewer #2: The manuscript compared the effectiveness of four ways to link BMPs to land characteristics during optimization. The results were well presented and can direct the work of BMP placement in the future. The work has its merits, but issues were found that can have serious negative impact to its acceptance by academia. The main problem of this manuscript is its organization. The author preferred to provide a rough and generalized description first, and then provide more details in a later section. This is not wrong, but the general description is often too generalized that readers cannot understand what the description actually referred to. This is particular serious before section 2.3 (but later sections also have this problem). The general description must contain enough information and definition so readers can understand it right away without referring to other parts of the manuscript. If detailed information must be left in a later section, the general description should contain a “pointer” to point readers to the correct section (e.g. “section x.x contains more detailed information about xxx”) that contains detailed information. The second problem (which is related to the first problem) is that many terms were not defined when they were used the first time in the manuscript. For example, the abstract is very hard to read because of all the undefined terms such as “spatial unit”. The abstract and the introduction parts must be reorganized.

    • Reviewer #3: his is a solid piece of work addressing the watershed best management practice (BMP) scenarios optimization with regard to effectiveness, optimizing efficiency, and practicality by comparing different BMP configuration units based on one same watershed. The manuscript is written clearly and highlights the need for research on this topic. The authors provide sufficient methodological detail and the research findings are robust with practical implications.

  • Resubmitted: 2019-01-24

  • Major revision (From reviewer #2): 2019-01-25

    • Reviewer #2: Thank you for providing an updated copy of the manuscript. The reviewer saw a lot of improvements, but issues still exist. This manuscript has good technical merit, so I would really like to see it published with improved writing. I would seriously suggest the authors to refine writing in the manuscript. One of the authors lives in the U.S., and I highly recommend him/her (and/or his/her American colleagues) to review the manuscript for clarity.

  • Resubmitted: 2019-01-28

  • Accepted: 2019-01-31


Zhu, L.J., Qin, C.Z., Zhu, A.X., Liu, J.Z., and Wu, H. 2019. Effects of different spatial configuration units for the spatial optimization of watershed best management practice scenarios. Water, 11(2): 262. doi:10.3390/w11020262

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