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41 APPENDIX B GREENBANK DECISION SUPPORT TOOL USER'S GUIDE HOW THIS SOFTWARE WORKS Water column habitats Benthic habitats The Greenbank Decision Support Tool assists users in The riparian zone and related terrestrial habitats or selecting and learning about environmentally sensitive tech- water quality niques for protecting transportation infrastructure located Public acceptance adjacent to stream channels. Specifically, Greenbank recom- mends streambed and bank erosion control measures suitable If interest is expressed in any of the first three of these cat- for a given site. Greenbank screens a master list of several egories, queries regarding the associated attributes appear: dozen environmentally sensitive bed- and bank-protection Water column habitats: techniques using responses the user provides to 12 to 20 questions. These questions deal with key environmental Providing instream or overhead cover for fish and other issues associated with the project, the nature of the stream aquatic organisms reach where the project is located, key erosion processes, and Providing and enhancing fish rearing habitat cost factors. The master list of techniques is narrowed down Providing habitat for adult fish using the responses until a short list of suitable techniques is Creation of velocity refugia derived. Selection criteria are based on the best available Pool and riffle enhancement information from the literature and sound fundamental prin- Benthic habitats: ciples derived from the collective experience of engineers and scientists working with streams over many decades. Providing or enhancing quality stream bottom (benthic) The system eliminates techniques that published sources habitat indicate are not able to withstand forces produced by design Decreasing the amount of sediment deposition occur- flows at the site in question. Additional queries include or ring within the adjacent reach and downstream reaches eliminate techniques based on cost and on the way the tech- Reducing the frequency of bed movement or the sever- niques control erosion. For example, continuous measures ity of erosion like stone blanket typically halt erosion entirely, while dis- continuous measures like bank barbs or spur dikes deflect The riparian zone and related terrestrial habitats or water flows but may allow limited erosion between structures quality: after construction until a stable, "scalloped" bank line is formed. At the end of a consultation, Greenbank provides a Riparian habitat ranked list of the recommended techniques with explana- Water quality improvement tory notes about each one. For each recommended tech- nique, the user may also request a list of techniques that These queries ask the user to assign a value of very impor- may be combined with the recommended technique to tant, somewhat important, or not important to each of the improve the net environmental outcome. A list of all of the 10 attributes. If the user indicates public acceptance (the 11th techniques that were not recommended is also available to attribute) is of interest, the program automatically assigns a the user, with notes for each technique explaining why it value of very important to that attribute. If the user does not was not recommended. assign a value of very important or somewhat important to at least one of the eleven attributes, then a warning message is displayed. INITIAL INPUTS "You have not selected any environmental resource or Environmental Attributes attributes as important. Greenbank is designed to help you select techniques to address environmental issues. You may The user provides responses to a series of multiple-choice wish to use the back or restart buttons to revisit previous questions regarding the importance of various types of envi- questions. However, you may continue if you wish." ronmental attributes for the project in question. Each of 11 specific attributes is rated as very important (2), somewhat Erosion processes important (1), or not important (0). All values are initially set to 0. In order to make dialog more efficient, the user is ini- Greenbank attempts to select bed and bank erosion control tially asked for interest in the following four categories: measures that address the dominant erosion processes operative

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42 at the site in question. Through dialog with the user, the system Overbank runoff links symptoms with causes and selects important erosion Piping due to steady seepage processes from a list of 13. The logic allows for the fact that one Episodic failures due to piping from sudden drawdown process may trigger multiple symptoms and that a given symp- or return of overbank flooding to channel tom does not always have the same cause. Furthermore, more than one erosion process may be important for a given site. Erosion or Scour by Waves or Currents The dialog begins with Greenbank requesting the user to characterize the erosion problem at the site in question as one If the user selects "Erosion or scour," Greenbank asks the of the following: user to classify the spatial extent of the problem as either local or general. Greenbank also asks where erosion appears Development of gullies or rills to be occurring: on the bed, at the bank toe, on the middle of Erosion or scour by waves or currents the bank, or on the top of the bank. Based on these responses, Bank collapse or mass failure the user is asked to specify important processes. Allowable choices are indicated in Table B-1. Development of Gullies or Rills Bank Collapse or Mass Failure If the user selects "development of gullies or rills," Green- bank requests the user to specify one or more of the three If the user specifies that the bank problem is collapse or causes: mass failure, Greenbank asks the user to classify the spatial TABLE B-1 Possible processes involved in erosion or scour by waves or currents Spatial extent of erosion (specified by user) Region where erosion is General (similar processes occurring (specified by user) Local (limited to a bank appear to be occurring for a segment a few channel widths considerable distance up- and long) downstream) Local scour due to flow General bed degradation. obstruction, constriction, or Bed channel irregularities. Headcutting. Headcutting. Local scour due to flow obstruction, constriction, or channel irregularities. Toe erosion and upper bank Toe collapse. Removal of noncohesive layers or lenses in stratified alluvium. Local scour due to flow obstruction, constriction, or Middle and upper bank scour by channel irregularities. currents. Middle of bank Removal of noncohesive layers or Ice and debris gouging. lenses in stratified alluvium. Local scour due to flow Ice and debris gouging. obstruction, constriction, or channel irregularities. Top of bank Navigation or wind wave wash. Removal of noncohesive layers or lenses in stratified alluvium.

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43 extent of the problem as local (limited to a segment of bank If seepage or drawdown is a factor and if bank slope shorter than a few channel widths long) or general. > 20 degrees, then the advisory reads, If the problem is local, the user is asked to specify one of the following three processes as primary: "There is a potential mass instability problem at the site. Possible solutions include techniques that reinforce the Toe erosion and upper bank collapse slope, flatten the slope, support the slope with lateral struc- Headcutting ture, or improve subsurface drainage." Piping If the user selects cohesive soil as the bank material type, If the user selects piping, Greenbank asks if the piping Greenbank computes an allowable bank slope angle crit appears to be due to steady seepage or due to sudden draw- using these relationships: down or return of overbank flooding to channel. If the problem is general (similar processes appear to be Ns = H /c occurring for a considerable distance up- and downstream), crit = -25Ns + 190 the user is asked to categorize the problem as follows: where Ns is the stability factor and crit is the square root of the angle beta. Toe erosion and upper bank collapse This formula was obtained by fitting a linear regression to General bank instability or susceptibility to mass slope published tabulated values.1 If the computed crit > , then the failure following advisory appears: A user who specifies slope instability is asked to specify "You have indicated that general bank instability is one of whether or not the instability is related to subsurface water the primary erosion processes operating on your site. How- movement. ever, simple stability checks indicate that the bank height, slope and soil type you have described should be stable. You may continue, but you may wish to use the back or restart GEOTECHNICAL STABILITY CHECK buttons to revisit previous questions." If the user specifies that the main reason for bank collapse is general bank instability or susceptibility to mass slope fail- If the user specifies the bank material is a sand-clay mix- ure, then Greenbank runs a simple geotechnical stability ture, Greenbank follows a procedure similar to the one for check. First, the user is asked to specify the type of bank clay but uses the following relationship for Ns. material: Ns = [0.056684+0.0048688*SQRT()*ln() -0.027777262*SQRT()]-1. Sand Cohesive soil This relationship was obtained by fitting a nonlinear Sandy soil regression function to published values1. Then Hcrit = Ns(c/), A mixture of sand and clay and if H < Hcrit, then the following advisory is Alternating sand and clay layers. displayed: Gravelly Noncohesive materials coarser than gravel "You have indicated that general bank instability is one of Resistant bedrock the primary erosion processes operating on your site. How- ever, simple stability checks indicate that the bank height, The user is also asked to provide the bank slope, bank slope and soil type you have described should be stable. You height (H), angle (), soil density (), friction angle (), and may continue, but you may wish to use the back or restart cohesion. The following steps are then used for a preliminary buttons to revisit previous questions." geotechnical stability check: If the user selects sand as the bank material type, Green- If the user indicates the bank is alternating sand and clay bank asks if seepage (subsurface water movement) is a fac- layers then the following advisory message appears: tor in slope instability. If seepage is not a factor, and if bank slope > 35 degrees, an advisory is added to the comments that "You have indicated that general bank instability is one of appear at the end of the run, the primary erosion processes operating on your site. Green- bank normally checks bank stability using bank height, angle "There is a potential mass instability problem at the site. and soil properties. However, such simple analyses are not Possible solutions include techniques that involve flattening the slope, providing internal reinforcement, or supporting 1 Journal of the Soil Mechanics and Foundations Division, American Society of Civil the slope with a lateral structure." Engineers, Vol. 97, No. SM1, January 1971, pp. 22-23.

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44 possible for complex stratigraphy (alternating layers of BUDGET cohesive and noncohesive soils). You may wish to consult a geotechnical engineer for allowable bank heights and angles The user is asked to input the maximum acceptable price or run the ARS bank stability model after carefully studying for initial construction. However, this input is not a dollar the documentation. You may also use the back or restart but- amount but a ratio that represents the price relative to the tons to revisit previous questions." price for protecting the site with stone riprap blanket. The actual input is therefore a number between 0.5 and 20 that No simple checks are run if the user specifies gravelly represents the price the user is willing to pay divided by the banks or noncohesive materials coarser than gravel. If the cost for riprap revetment applied from bank toe to bank top user specifies that the banks are resistant bedrock, the fol- at the site in question. lowing message appears: Maintenance effort may be measured in monetary or other terms. The user is asked to specify the maximum level of "You have indicated that general bank instability is one of maintenance that can be provided in qualitative terms: mini- mal, moderate, or high. the primary erosion processes operating on your site. How- ever, you have also indicated the banks are composed of resis- tant bedrock. It is very unusual for bedrock banks to exhibit general instability. You may continue, but you may wish to use MISCELLANEOUS INPUTS the back or restart buttons to revisit previous questions." Greenbank asks if the user wishes to compare hydraulic loading at the site with criteria for the techniques under con- ALLUVIAL STREAM TYPE AND EROSION RISK sideration. Local velocity, shear stress, or both may be eval- uated, depending upon available criteria. Elements of a simple stream classification system have The user is also asked if additional land loss (due to contin- been incorporated into Greenbank as an additional tool for uing erosion or bank grading) would be acceptable at their site. assessing the likelihood of significant site erosion. Green- The user is asked for an assessment of the hazard, or con- bank queries the user for values of several descriptive vari- sequences, of failure. Choices are extreme (almost certain ables (for example, flow habit, bed material, bank material, loss of human life), severe (possible loss of human life and planform, location and size of bars, channel width, and so almost certain significant loss of adjacent structures), mod- forth) using a series of multiple-choice questions with largely erate (possible loss or severe damage to adjacent structures), qualitative answers. These responses are used to place the and light (the probability of loss of life or severe damage to candidate site in one of five stream type categories defined by adjacent structures is very small). Brice et al. (1978).2 If the site does not fit criteria for any of the Brice categories, it is classified as an unknown type. The five Brice stream types are used to further categorize the site TECHNIQUE SELECTION as high, medium, or low erosion risk. Bed- and bank-protec- tion techniques are then eliminated if they are not judged The Greenbank system examines each of the techniques appropriate for the erosional regime of the site. using the inputs described above by comparing the user- supplied values with those in a large spreadsheet, or matrix, A similar approach is used to categorize the site according that contains a row for each technique. Suitability of each to the incised channel evolution model (CEM) developed by technique is encoded within the matrix as follows: Schumm et al. (1984)3 (see Figure B-1) and Simon (1989).4 A stream reach is classified into one of five evolutionary The matrix contains a column for each of the 11 environ- phases or, if none of the phases seem to fit, as a reach where mental attributes and a column for each of the 11 erosion the CEM does not apply. Again, these results are used to clas- processes. sify the risk of instability. CEM stages I, II, III and IV are Entries in the environmental attribute columns are either 0 classified as high erosion risk, while stages V and VI are low (the technique does not contribute positively to the attribute), risk. Sites that do not seem to fit or that exhibit none of the 1 (the technique has potential for a mild positive impact on symptoms of incision upon which the CEM is based are clas- the attribute), or 2 (the technique generally has a major, pos- sified as low risk. itive effect on the attribute). For purposes of this selection system, simply controlling erosion generally does not con- stitute positive contribution. 2 Brice, J. C., et al. Countermeasures for Hydraulic Problems at Bridges. Report No. Entries in the erosion processes columns are either 0 (the FHWA-RD-78-162, FHWA, Offices of Research and Development (1978). technique does not address the process) or 1 (the technique 3 Schumm, S. A., Harvey, M. D., and Watson, C. C., Incised Channels: Morphology, does address the process). Dynamics and Control. Water Resources Publications, Littleton, CO (1984). 4 Simon, A. "The discharge of sediment in channelized alluvial streams." Water The matrix also contains a column giving estimated unit Resources Bulletin, Vol. 25, No. 6, 1989, pp. 1177-1188. cost relative to riprap stone blanket.

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45 Figure B-1. Schumm's Channel Evolution Model The matrix contains a column entitled "Level," and each Level I, little or no long-term monitoring, fewer case technique is rated as follows: studies and citations in technical literature, cost data Level I--well established and widely used, well docu- scarce or less certain. mented (good performance and monitoring data avail- Level III--emerging, promising technique. Does not able), reliable design criteria based on lab/field studies, have the track record and level of information charac- numerous citations and case studies in technical litera- terizing Level I or II. No field or laboratory design or ture, cost data available from variety of sources. test data, no long-term monitoring or performance data, Level II--used often but lacks the level of detail, qual- very few literature citations or case studies, no reliable ity of information, and reliability that characterizes cost data.

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46 TABLE B-2 Treatment levels Assignment Criteria Treatment Level I II III Frequency of Use Widely and frequently Occasional and more Infrequent use in very used limited use limited areas Availability and Good... abundant and Fair... more limited and Poor... little or no data Reliability of Lab/ reliable data less reliable available, mostly anecdotal Field Test Data Performance and Good... long term and Fair... short term and less Poor... little to none Monitoring Info well documented reliable available Literature Articles and Many... in well regarded Some... few if any case Few... mostly fugitive and Case Studies journals and agency studies obscure publications publications Availability and Good...detailed unit costs Fair... less detailed and Poor... little available and Reliability of Cost Data from several different fewer sources of limited applicability sources and locations Table B-2 summarizes the attributes of the three levels. they correspond to the largest size material commonly used for The matrix contains a column indicating the potential for stream and river bed and bank erosion control.5 additional bank erosion occurring after the technique is The matrix also contains a series of columns for several installed. For example, intermittent techniques like bend- key reach characteristics as follows: way weirs or bank barbs often create "scalloped" banklines due to local erosion between structures. Values of 0, 1, or 2 The matrix contains columns for each of nine key vari- are assigned for no, moderate, or strong potential, respec- ables describing reach morphology and other site character- tively. Values of 99 are found in rows for techniques istics. Each technique is given an integer score for each vari- where this aspect is controlled entirely by site-specific able. The nine variables are shown as headings in Table B-3, characteristics. which also provides an explanation of what the integer scores The matrix also contains columns for allowable shear stress in the matrix mean. and velocity. An adjacent column provides the source for these data (numbers for literature citations in a numbered reference list). If no critical velocity or shear stress values were found in 5 D50 = 0.75 m using approach of Maynord (1993) in Escarameia (1998) p. 40. Maynord, S. T., "Corps Riprap Design Guidance for Channel Protection." In River, the literature, the entries are 99. Values of 3.5 m/s and 2.5 m/s Coastal and Shoreline Protection: Erosion Control Using Riprap and Armourstone, C. appear in rows corresponding to structures built with angular R. Thorne, S. R. Abt, F. B. J. Barends, S. T. Maynord, and K. W. Pilarczyk. (eds.). John Wiley & Sons, Ltd., Chichester, U.K. (1995) pp. 41-42. and rounded stone, respectively. Clearly these values depend Escarameia, M., River and Channel Revetments. Thomas Telford, Ltd., London on the size of the rock used, but these values were adopted as (1998).

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TABLE B-3 Explanation of matrix scores for site description variables. The Greenbank master matrix contains a row for each erosion control technique. Each technique is given an integer score (shown in first column of this table) for each of the site variables (bold faced in this table). Cells shaded dark gray represent integer scores that do not appear under the given heading Channel Stage of Maintenance Entry in matrix Flow habit Flood plain widtha Bed material Bank material Braiding Erosion risk width incision requirements No incision Low Cohesive to noncohesive Not suitable for a Suitable only for sites 1 < 15 m < 2Wb Silt to sand sandy braided stream with low erosion risk Moderate Suitable for sites with Ephemeral or More than 2W but Cohesive to noncohesive Possibly suitable for a Stage VI or no 2 < 50 m Sand to gravel low to moderate erosion intermittent less than 10W gravelly braided stream incision risk Perennial or Cohesive to noncohesive High Suitable for a braided Stage V, VI or Suitable for all sites 3 no 10W Gravel to cobble materials coarser than stream no incision without respect to risk limitations gravel Stage IV, V, VI 4 > 500 m > 2W Cobble to boulder No limitations or no incision Stage III, IV, 5 > 15 m Silt to gravel V, VI or no incision No 6 Gravel to boulder No limitations limitations 7 Sand to cobble 8 No limitations a Area flooded by 50 to 100 year event. b W = active channel width.

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48 EVALUATION OF A GIVEN TECHNIQUE allowable values for the techniques under consideration. A worksheet is available that provides computational Each of the techniques contained in the Greenbank master assistance in generating velocity and shear stress esti- matrix is assigned a numerical score that represents the suit- mates. After this, the system asks for either the design ability of the technique for the user's project. Initially, all shear stress or velocity. If the input shear or velocity scores are zero. For each technique the system computes a exceeds the tabulated value in the matrix, 100 is subtracted score as follows: from the score. Therefore the score for the ith technique is given by: If an environmental attribute rated as very important or somewhat important has a score in the matrix > 0, the system 11 EE 11 adds (the entry in the matrix/importance of the attribute) to Si = i ,k + Bi + EPi ,k + ( AEPi * AEA) + Hi k =1 EI i ,k k =1 the score of the technique. Matrix entries are 0, 1, or 2, while 9 importance values are 1, 2 or 3 as shown in Table B-4. + Hi + SFi ,k If the maximum relative cost specified by the user is k =1 greater than or equal to the relative cost in the matrix, the sys- where tem adds the quantity (1/relative cost) to the score. If the rel- ative cost is more than the user-specified maximum, then the Si = score for the ith technique. system adds the quantity (budget - relative cost), which will EEi,k = score indicating effectiveness of the ith technique in be a negative number, to the score. enhancing the kth environmental attribute (either 0, 1, or 2). If an erosion process that the user rated as important has EIi,k = score indicating the user-specified importance of the an entry of 1 in the matrix, the system adds 5 points to the kth environmental attribute at the site in question (either 1, 2, score of the technique. If an erosion process rated as impor- or 3). tant has a value of 0 in the matrix, the system subtracts 100 Bi = term based on the unit cost of ith technique relative to points from the score. unit cost for ripap blanket. Bi = 1/relative cost if the relative If no additional land loss is acceptable and if the technique cost is less than the user's budget. If the relative cost is more is likely to allow some additional erosion to occur after it is than the user's budget, Bi = budget - relative cost. installed, the system subtracts 100 from the score. If addi- EPi,k = score indicating the effectiveness of the ith tech- tional land loss is acceptable and if the technique will require nique in addressing the kth erosion process. If the erosion slope flattening to create a slope more gradual that the max- process has been rated as important by the user and if the ith imum recommended slope for the technique, the system sub- technique addresses that process, EPi,k = 5. If the ith tech- tracts 10 points from the score to separate techniques that nique does not address the kth process and it has been rated require bank shaping from those that do not. as important, EPi,k = -100. The system asks if the user would like to compare the AEPi = score indicating if the ith technique may result in hydraulic loading for the site in question with published additional land loss due to bank shaping or erosion after con- TABLE B-4 Values added to technique score based on environmental attributes of interest and the effectiveness of the technique in addressing the given attribute (shaded area) Value in matrix for effectiveness of techniquea Importance of Importance 0--no effect on 1--mild 2--major environmental score this attribute positive effect positive effect attribute Very important 1 0 1 2 Somewhat 2 0 1/2 1 important Not important 3 0 1/3 2/3 a Values are computed by dividing the value in the matrix by the importance score.

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49 struction. If there is potential for some additional erosion, A similar approach is used to obtain an adjusted score for AEPi = -100, otherwise, AEPi = 0. the environmental performance of each technique. AEA = score indicating if additional land loss is acceptable Adjusted scores are converted to letter grades using the at the site in question or not. If so, AEA = 0, if not AEA = 1. scale in Table B-5. Hi = score indicating the capability of the ith technique to All techniques with grades of D or better (based on total withstand design hydraulic conditions. If the system contains score) are added to a list of recommended techniques. The an estimate of allowable velocity or shear for the technique list is sorted from highest-scoring techniques to lowest. and if the design shear or velocity for the site in question If no techniques receive scores greater than F, the system exceeds the allowable, then Hi = -100. Otherwise, Hi = 0. displays a message, SFi,k = score indicating the suitability of the ith technique for application to sites with conditions specified by the kth "Based on the information you have provided, Greenbank is site factor, as described in Table B-3 above. If the technique unable to recommend any environmentally sensitive channel- is not suitable for the specified site condition, then SFi,k = or bank-protection techniques. You may wish to reconsider -100, otherwise, SFi,k = 0. some of your responses. You may inspect and change your inputs by clicking on the back button. Press OK to end this run." Reporting Results If one or more techniques receive grades higher than F, the system displays the name and a brief description of the For each technique with a total score > -100,000, the fol- highest-scoring technique. The brief description includes the lowing formula is used to adjust the total score so that it falls letter grades awarded to the technique and its unit cost rela- between 0 and 10: tive to riprap blanket. The user is then given four choices: Adjusted score = 1. See next highest-scoring technique, 10*(total raw score) / [(2*(number of environmental 2. See a list of techniques suitable for combination with issues of interest) + 5*(number of significant erosion the recommended technique, processes) +5)] 3. See a list of all recommended techniques, or 4. See a list of all of the techniques that are not recom- mended. The denominator of the right hand side of the above expression represents the maximum score a technique can Selection of option 1 produces the name and a short receive. The first term allows for the fact that 2 is added to description of the next technique, along with a listing of the the total raw score for each important environmental issue same four choices unless there are no other techniques in the that is fully addressed by the technique (Table B-4). The sec- list of primary recommendations. ond term allows for the fact that 5 is added to the score for Option 2 is provided because best practice usually each significant erosion process that is fully addressed by the involves a combination of erosion control techniques. Green- technique, and the last term represents a maximum increase bank suggests primary techniques that address the important that can occur in total raw score due to cost factors. erosion processes and address environmental issues of inter- TABLE B-5 Relationship of adjusted scores to letter grades Adjusted Score Range Letter Grade >8 A 8 > adjusted score > 6 B 6 > adjusted score > 4 C 4 > adjusted score > 2 D <2 F

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50 TABLE B-6 Excerpt from matrix used by Greenbank to suggest secondary techniques to combine with primary recommendations Large Vegetated woody Longitudinal Longitudinal Vegetated Secondary earthen Bendway debris Weirs or dikes with toe peaked stone gabion technique spurs s Spur dikes Vanes weirs structures check dams spurs toe Coir rolls basket Vegetated earthen spurs 0 0 0 0 0 0 0 0 1 1 Spur dikes 0 0 0 0 0 0 0 1 1 1 Vanes 0 0 0 0 0 0 0 1 1 1 Bendway weirs 0 0 0 0 0 0 0 1 1 1 Large woody debris structures 0 0 0 0 0 0 0 0 1 0 Weirs or check dams 0 0 0 0 0 0 0 0 1 1 Longitudinal dikes with toe spurs 0 0 0 0 0 0 0 1 0 0 Longitudinal peaked stone toe 0 0 0 0 0 0 0 0 0 0 Coir rolls 1 1 1 1 1 0 1 1 0 0 Vegetated gabion basket 1 1 0 0 0 0 0 0 0 0 est. However, other techniques that are compatible with the while techniques that might be added to the primary technique primary technique may be applied at the same site in order to for superior environmental performance are shown in the first enhance the net environmental outcome. For example, lon- column. Entries of 1 indicate compatibility, and entries of 0 gitudinal peaked stone toe is effective in controlling toe ero- indicate incompatibility. These entries were composed based sion by current or waves, but aquatic habitat may be on experience and professional judgment. Table B-6 shows enhanced by adding spurs or vanes to the toe protection. that vegetated earthen spurs might be added to coir rolls to If the user requests a list of techniques suitable for combi- improve overall environmental effect, but they are ruled nation, another large matrix is searched. This matrix is used incompatible with vanes (they are too similar to vanes). in a fashion very similar to the first selection matrix, but the Selection of option 3, "See a list of all recommended tech- procedure differs in three important ways. First, erosion niques," provides the most complete set of information. processes are not considered, because it is assumed that the Many of the key inputs are echoed, along with Greenbank's primary technique will provide erosion control. Second, costs evaluation of the Brice alluvial stream type and erosion risk. are not considered. Third, the matrix contains additional A short description of each recommended technique sorted columns that indicate which techniques are compatible. How- from highest to lowest score is provided. Links are provided ever, most of the site variables (for example, channel width to additional information screens. For example, all tech- and bank material) are considered. Each row in the matrix niques that involve vegetation are linked to screens giving represents a technique and there are also columns for each information about soil compaction, plant handling, propaga- technique. A small excerpt from the matrix is shown in Table tion, and irrigation and to a document providing information B-6 above. Primary techniques are shown as column heads, about effects of plants on channel flow conveyance.